So you want them to make a sequel to AMSP with the same exact aesthetic? That aesthetic was not the norm of Radiohead, it was actually a betrayal of the band's core identity up to that point, which had entailed a rejection of nostalgia. To repeat what was already a retro aesthetic, some years later, would be an even further betrayal.
AMSP, far from being assembled from diverse odds and ends by random chance, has the most unified aesthetic of any Radiohead album, with the entirety of the thing being recorded using old technologies and making use of late '60s/early 1970s style psych rock/baroque folk instrumentation.
Jonny teased in initial comments that the project would mix very new and very old technology. This may have been the initial plan, but it turned out not to be true at all, much to penny's chagrin (remember his theory that this would be a Life of Pablo-style performance art piece where the actual album would be created in real time by live performances, and subject to listener choice).
In fact, the album uses exclusively old music technology where it counts: what the listener hears. It might make use of some digital editing processes, but if so, they are designed to be completely inconspicuous and inaudible. Even Daydreaming's vocal effects still resemble what was achieved with analog means in the original Twin Peaks sound design, or numerous tape looped backwards effects in '60s-70s rock.
I repeat my earlier challenge: please find a song, or even a moment on AMSP that sounds like it could not have been created before 1975-6 (at which point Thom was 7-8 years old). Such moments do not exist, such songs do not exist. When you set out to create, in 2015-6, an album that sounds more than 40 years old, evoking the music of your earliest childhood, and contains zero moments of production, instrumentation or songwriting that break the fourth wall to inform you in fact it is 2016 (the closest one is lyrical-- "strike up the tinderbox"-- but even that is vague enough to refer to the original meaning of tinder) that is a very clear aesthetic statement, possibly even an ideological statement.
It is not simply a choice. It is a choice that requires immense, immense effort to realize, much as it requires immense effort to clear the streets of modern cars and paint out all instances of modern technology when making a period piece. It is very costly (check out the rates for La Fabrique studio) and it is very hard in practical terms to create such a bubble around oneself and live artistically in the past. No one undertakes such a choice accidentally, or sees such a choice through without fully intending the outcome.
Even most of the supposedly "retromanic" albums that have been created by millennials have many more eruptions of the present than AMSP. Even Bruno Mars has some things that betray him as a modern artist (which actually makes his music more honorable than if it was purely pastiche). It's extremely rare to find an album that received such high acclaim as AMSP and is solely a pastiche of an earlier era. In a sense, critics gave Radiohead a pass for being reactionary, whereas they usually attack other artists for doing the same (even if the result is technically a perfect recreation, and is enjoyable).
I understand that this forum contains some people older than the band, and if so, perhaps these posters stopped listening to new music as avidly around that time, and the music that existed in the early '70s when the band members were prepubescent, is simply the norm of what music should be. When new music returns to that exact sound, it is their Proustian madeleine, nostalgically appealing to a baby boomer or an older gen xer rock fan in much the same way as an '80s- or '90s-sounding modern album is nostalgic for millennials. I understand this. I also happen to like the early '70s sound more than perhaps any other rock sound, even though that's not even my generation. Feist's Metals is another example of a 2010s album that, like AMSP, relies on a very retro sound, and I consider Metals a near masterpiece.
Why "near" though? Why is Metals never going to be comparable to For the Roses, even though it is arguably more consistent? Why is AMSP not deserving of comparison with Meddle? Because there is something wrong when it is considered in some way avant garde, alternative, independent and tasteful to offer a mere mimicry of what was fashionable 40 years ago, without any effort (as Lana Del Rey controversially, and admirably, makes) to engage with the present and the progressions and regressions that have been brought about by time.
LDR is uncomfortable for many older listeners who remember the '60s/70s, because of the way her music foregrounds the way things have changed and not changed since the good ol' days they idealize. Rather than trying to convincingly recreate the '60s/70s (or to recreate the early '90s alt rock scene that produced Creep, for that matter) Lana does something more philosophically mature, calling intentional attention to the artifice of any such recreation and making music about the perils and pull of nostalgia. What Radiohead does on AMSP is more comfortable and therefore less artistic: they method-act the role of a 1970s classic rock band with such aplomb that most listeners painlessly absorb their new music as nostalgia, rather than as a critique of nostalgia.
My suggestion for Radiohead's future development in this thread is predicated on the band's abdication in recent years from the role fans had once believed they occupied, as musical progressives. If they are not to be progressives, and indeed if their attempts at progression are to be greeted with sneers and jibes that it sounds like "a mechanic's garage" and isn't even music (as TKOL was greeted here and elsewhere, even still at the time of AMSP's release) then all that remains is to find the styles of the past that are best suited to Radiohead's instrumental skill set (which actual, improvised jazz and avant garde work, for example, is not) and which split the difference between the band's own sophistication and their more musically conservative listeners (which TKOL apparently failed to do, a sign that they certainly shouldn't try anything more "experimental" than that).
The most complex yet satisfying style that can push their skills in new areas while still appeasing their middle of the road fans, lies in this area of smooth jazz/sophisti-pop/blue eyed soul. It's also something that might help Thom make some real improvements as a vocalist and songwriter (because it demands more vocal and lyrical character and specificity, as the music is unpretentious and professional to the point of seeming "boring" unless paired with strong, singular lyrics). Judging by their flirtations with these sounds on parts of the last three albums, this sound also seems to give the band members joy to play, which makes sense, considering they've spent decades wanting to play it before finally allowing themselves to.
For some bands, there would be another way out of the corner Radiohead have painted themselves into, the opposite of smooth jazz/blue eyed soul: a punk record. This option was still open to Radiohead until last year. Punk, however friendly it has historically been to fascists within its midst, requires a moral authority (a belief by the audience that the singer is a credible rebel, whether or not they actually are) that Radiohead, fronted by a rich guy who breaks a picket line to play Israel, cheats on his dying partner and sells $130 reissues, no longer possess in the eyes of even their biggest fans. It isn't that we would spurn a punk record as a decent piece of music, but one measure of punk is whether it is taken seriously, and nothing of that nature could be.
Who wants to hear Thom being angry on our behalf, let alone (another key part of punk) turning his anger on us? Who would enjoy that? Punk would be merely a pose, like prog folk or any other genre of the past to be excavated. As such, they might as well excavate other genres that better suit their role as musicians at the present time.
No one should be under the assumption that being Everything But the Girl was as easy as they made it seem. The ease of soft and smooth sounds can be disarmingly difficult to create, requiring levels of musical skill and maturity and rigor and fearlessness that most musicians will never have and even the band members of Radiohead may only be approaching now in late middle age, and may yet have work to do. Such a sound may turn out to be unattainable, as well, especially given the weakened vocal instrument Thom has to work with. Even at vocal peak, he's never been a Tracey Thorn.
If they pursue this direction to its end point however, I do have faith they will discover something there which we have yet to hear, or at least something we haven't heard from them, and maybe even something a lot of fans have difficulty imagining, so that's more exciting than rehashing their own past.