Although I love artists that rework their songs live periodically, Genesis historically has not done this. They may change the tempo, drop a verse, change the keyboard sound, change the key. But the song remains much the same as the recorded version. The exception is the acoustic versions on the Genesis Songbook DVD.
As we have discussed many times, when Genesis plays larger shows, a significant portion of the audience mainly knows the radio hits and is unfamiliar with what many of us on the forum feel are the more interesting songs. I think that the band views those familiar with the hits just as legitimately part of the audience as those who nod knowingly when they quote Stagnation in I Know What I Like. So I think they will still try to please both. They will play many of the well known ones that many of us are a bit tired of. They will also pull out a few old chestnuts, I hope with a few surprises. Post hoc we will quibble about the balance between these two choices, as we always do.
As for changing up the setlist throughout the tour, as people have noted above, they tend not to do this. The most common practice is to try out some songs early in the tour and drop the ones that aren't working. They seem to be comfortable playing the same setlist night after night, so I can't imagine they would want to do differently.