I suppose all of realingment junkies see two major criteria:
1) Setting up a National Championship structure where every team has to jump through the same hurdles, and
2) Some respect for Geography.
Item 1) may dictate now that we go with 12-team 2-division conferences across the board (I really prefer the 10-team, 9-game round-robin model that the PAC-10 now has, but I can't see us going backward).
Item 2) suggests doing something about geographical out-liers like BC, South Florida, Louisiana Tech, UTEP, TCU, Hawaii. Some movement here is possible as larger conferences expand to 12, and we get a cascade effect. However BC and South Florida are probably already in their final resting place.
ACC, SEC, Big12, - no change
Big Ten gets ND. Not sure Notre Dame will ever want to give up its independence but if being in a conference vs. being an at-large was so much more advantageous, who knows ?
Big East adds: Central Florida, East Carolina, Memphis, and another team such as Marshall or UMass, or a team from the MAC.
PAC-10 becomes PAC-12 by adding: 2 of Utah, BYU, UNLV, SDSt., Hawaii - whoever - I won't debate who, since there are negatives for all the candidate schools.
Mountain West goes to 12 (after losing probably 2 to PAC-12) by adding 5 teams: UTEP, Fresno St., Boise State, Nevada-Reno, and Hawaii.
CUSA (having lost 3 to the Big East and UTEP to the Mountain West) adds La. Tech, North Texas, and two other schools from the MAC, Sun-Belt, or Southland (1-AA).
The WAC is rather decimated, they talk some sort of merger with the Big Sky and debate whether 1-A or 1-AA is more viable.
If the MAC loses teams, they look at restocking by addition of: Army / Navy, Youngstown State (1-AA), making Temple permanaent, WKU, Middle Tennessee (or a team like Illinois State from the MVC / Gateway).
The Sun-Belt - who knows....
I think the best would be a 16-team playoff, with some automatic berths, a few at-larges (that are prioritized to go to a lesser conference champions, if they have a minimum number of 1-A wins, or some other criteria so that a stinky team doesn't pollute the playoff).