16 teams will work if its the right teams. Hell, 20 will work if its the right teams (at 20 you're basically 2 separate conferences flying under the same banner just working together for cash purposes). With the wrong teams, 8,10,12,16,20 wont work. Clearly the WAC16 was a failure because none of the teams could bring in enough money to support massive travel. But at the same time, the WAC just failed as a much smaller conference too. The big east was a fairly small football conference for some time, it has failed as well. Why? Because it doesnt bring in enough money. The big 12 failed over the last couple years before stabilizing. Why? Largely money issues (and disagreements thereof). How did it stabilize? Offering a better payday to the schools it brought in.
I think the big 12 can work as 14-16 if it expands and develops a national footprint, assembling some great brands nationwide, and most importantly, brings in enough money to keep its elements happy cashing checks.