For now, "semis" would be splitting into 2 football conferences (maybe they'll buy the MEAC out) and sending both to the playoff with no guarantee they play each other. You can't really do "semis" as 12th games without either relocating games the last week or having teams other than the Top 4 playing in them. A note about relocating games is that MOST teams could know their opponents weeks ahead of time, only the top teams might switch at the last moment.

Schools are fiscally dependent on knowing how many and when their home games will be.

Years ago I sketched out a proposal for the Big Ten to have the games the week BEFORE rivalry week as "flexible" games to try and get top teams who missed each other a chance to play one another and reduce (greatly) the chance that tie-breakers rely on any ranking system. The games had pre-determined home teams with visiting teams determined by algorithm 14 days ahead. There was also 2 more "visiting" teams than "home" teams and often the best two visiting teams played at a neutral site. I have the sim data somewhere, but it was something like 99% of tie-breakers were determined by head-to-head (though that, was 9 conference games with 14 teams, not 8 with 16).