I have a better scenario using 27 of the current 28 bowls:
The top 28 teams get into a playoff system with the top 4 teams receiving a first round bye. This leaves teams 5 thru 28 playing in 12 first round games utilizing "minor" bowls. The 12 winners would join the top four teams as the Sweet 16, and would play the second round games in 8 "mid-range" bowls. This would determine the Elite 8 teams to advance to the third round (quarter-finals) in four of the second-tier bowls (including one of the current BCS and three slightly off-BCS level bowls, Cotton and Peach for example). The Final Four would come from this round and would play in the fourth round (semi-finals) in two of the current BCS bowls. The championship game would then be the fifth week in this true Bowl Championship Series. The semi-finals, championship game and quarterfinals could rotate among the current BCS bowls. Under this system, the top 28 teams would get at least one bowl game (compared to 56 teams under the current bowl system in which just about everyone that manages to get to .500 is bowl eligible). Under this system all of those 28 teams have a chance to play for the national championship. The other beauty of this system is that all of these currently meaningless bowls would become meaningful because they would determine who advances in the playoffs. As such, the ratings appeal for all the minor bowls will be increased tremendously, and even the mid-range and upper tier bowls will become more important. Such a playoff would rival March Madness in the fan interest and intensity it would create.
Actually, there's 56 teams playing right now in 28 bowls. I doubt many of the second tier schools and conferences are willing to sacrifice their bowl game money and exposure for a large playoff system. The bowl committees and their sponsors also don't want to lose their piece of the pie.
I suppose you could structure a 48 team tournament with the top 16 receiveing a 1st round bye. That would mean 16 opening round games and 16 second round games, 8 third round, 4 fourth round, 2 semis and a championship game for a total of 47 games.
That's too big. I don't think the NCAA or the networks want to add that much programming. It turns the opening round games into regional broadcasts. That's a step backwards from the national TV audience they have now. And which network would want to run the opening round games counter to NFL programming on Saturdays and Sundays in December?
Besides, who really wants to see USC taking on the winner of 6-5 Southern Miss and 7-4 North Texas?
Let's push for baby steps instead.
Politics and logistics will keep the NCAA from creating anything more than an 8 team playoff (yes, 16 would be better). It would add only 3 games to the existing format, make the Rose, Sugar, Orange & Fiesta relevant EVERY year and make the national championship a lot more real.