To see how a new development might affect the future, take a look at how it would have affected the past. That's a go-to of mine -- see: how larger playoffs would have worked in 2020 or how a much bigger, earlier playoff would have affected things -- and with the news that we could be moving toward a 12-team playoff soon, we have a reason to dip into that well once more.
For all the simulations I've done, I had never really paid much attention to a 12-team format. An eight-teamer -- six conference champions with two at-large bids -- has long seemed perfectly inclusive and interesting to me. It was the logical next step. But as it turns out, a 12-teamer works quite well in terms of political calibration.
A 12-team playoff indeed offers a playoff path to what we have long referred to as the Group of 5 conferences, assuring that college football's national title race is actually inclusive for just about the first time ever. But it also assures that the most powerful conferences and teams benefit massively from extra at-large bids. And the news that quarterfinal games would take place in bowl games (presumably the four New Year's Six bowls that don't host semifinals in a given year) instead of home fields conveniently allows the most influential bowls to remain relevant. We lose home-field atmospheres, but the Rose Bowl doesn't end up with the Big Ten's fourth-best team against the Pac-12's third.
To best learn about what a 12-teamer changes, however, let's hop in the simulation machine.
Below are how each of the past seven College Football Playoffs would have taken shape with 12 teams instead of four. I used the playoff committee's rankings as they existed -- there's a distinct possibility that the committee considers teams differently with a 12-team cutoff instead of four, but we won't know what the changes are for a while. I also worked under the aforementioned assumption that the quarterfinals will take place in four New Year's Six bowls, with the semifinals taking place in the same bowls that hosted the four-team semis. I simulated each playoff using my SP+ rankings, and I'm including each playoff team's odds of reaching the semifinals below, as well as the most likely champions each season. (Why semifinal odds? Because I want to see what might have changed compared to the four-team playoff that we actually got.)