I think 6-10 is the right number. If you have automatic qualifiers at all then it has to be 8-10, without 6-8. I personally like 6 with 3-6 playing in round 1, then those winners taking on 1 and 2, but I think P5 AQ is going to happen with expansion. I would also remove and special treatment for Notre Dame. They do not get treated as a conference unto themselves. They get treated as any other independent. Join a conference if you want to play with the big boys.
Even in the NFL, where parity is much closer to real, it is rare anything below a 4 seed wins it all. I think 7 Wild Card teams have won it all since 1979 and 4 others made it. In college parity is so off that I find it doubtful any would ever even make it to the final game.