In a way it is a shame that Genesis is a band which doesn't do fluid set lists. There are all sorts of pros and cons, but if they are of the opinion that most fans are there for the familiar 80s and early 90s hits, with maybe 20-25 minutes of "old stuff"....rotating a few songs would be a workable way to get more older material done live one last time. Then the whole lot could be released on a live album/DVD/BD featuring everything. I don't have a ticket for a show but I wouldn't be disappointed missing FoF if I got Dance on a Volcano or the whole of Cinema Show instead...for example.
I once had this admittedly rather hair-brained idea that they could do a different side of The Lamb every night.
But that's not how Genesis have ever really done things. They might remove one song they feel isn't working after the initial UK/IRL concerts.
Thinking of medleys and how I generally don't like them, one exception is the "lamb stew" type. They could do a "Lamb casserole" stitching together some musical and lyrical highlights of The Lamb in a 15 minute chunk. Fly On A Windshield would sound awesome in an arena. Let of steam doing a bit of Evil Jam....bookended with the title track and Carpet Crawlers for familiarity. The other exception is Duke Ellington's famous medley which he performed in the 50s and 60s.
BTW I do agree with the band's assessment that much of the audience expects to hear the hits. Despite personally knowing what it feels like to be surrounded by 60,000 people chanting "me, I'm just a lawnmower" I think that for every fan such as myself who might wet themselves with joy if they launched into Hogweed or Stagnation, there'd be three others who would zone out. The Musical Box can fill the Royal Albert Hall for one night...Steve Hackett can do theatre tours based on old Genesis material and the better tribute bands can fill places like Shepherds Bush Empire for a couple of nights but not large arenas day after day.