and now you've left out undefeated boise state, one loss ball state (easily could have ended up undefeated), TCU (who ended Boise State's undefeated season in their bowl game), and the champion from both the ACC and Big East. Not to mention a very good Oregon State team that beat USC and only lost in a rivalry game and to a Penn State team that almost went undefeated.
The only way an 8-team playoff could be remotely realistic is is to take the six BCS conference champs plus two wild cards. Notre Dame would probably have their own clause to lock up one wild card if they finish high enough. The non-BCS schools would probably have another clause to lock up one wild card if one of them finishes high enough. So it's possible to have an 8-team playoff with no wild cards. This year an 8-team playoff would probably be:
1 Oklahoma v. 8 Va Tech
2 Florida v. 7 Cinncinnatti
3 Texas (wild card) v. 6 Penn St
4 USC v. 5 Utah