It's interesting, I think, in March Madness, that a 16 had never beaten a 1 seed, I think it happened recently. A 15 bears the 2 fairly often? Every 3 years or so? One could do the probability based on this, I suspect. How long would it take for a 12 seed to win a CFB NC? Longer than it will exist I suspect in current form, but it is possible. The seedings of course cannot be perfect, but they generally are not far off "reality".
Let's drop this down to say a 10 seed, which starts to be reasonably possible in say 20 years perhaps. They have to beat a 7 seed on the road, it'll happen of course, and then beat a 1-4 seed, and then a 1-4 see again, and then a 1-4 seed again, I think.
Their "odds" of winning each are something like 25%, then 20%, then 20%, then say 15%. They aren't a bad team of course, they lost a couple games probably in the year, maybe one was close, one was an upset, whatever, and they had 10 wins. If my math is right, they have a 0.15% chance of winning the NC. And maybe their odds are better because they got back a couple key players.
