OK, not saying this is GOOD PLAN ... but it is a plan that I think the power schools would like and might be a reasonable evolution for the playoff. It's kind of a compromise that might have the appearance of fairness.
THREE ELITE Conferences with 16 teams each. B16Ten, SEC16 (SEC + UT/OU), ACC16 (ACC + ND + someone)
Those E3 conferences get TWO AUTOBIDS to the Playoff each.
Three POWER Conferences with 12 teams each. BigXII (leftovers plus maybe BYU / BSU etc.), PAC12, AAC
The HIGHEST RANKED Champion of these three leagues get a bid to the Playoff (similar to current G5 arrangement)
Five Group of Five Conferences with 12 or so teams each. MWC, MAC, Sunbelt, etc etc etc.
IF the highest ranked Champion of these leagues is ranked higher than 12, then a bid to the Playoff...
If NOT, then the final bid to the Playoff is At Large to the highest ranked E3 team not already in the playoff.
Most years, that would a 8 team playoff between 3 teams from the SEC, 2 from the ACC and BigTen, and 1 from Pac12/ACC/BigXII... with an occasional G5 team if someone catches lightning in a bottle.