They tried this,
first, the question is irrelevant, because it will never happen. EA extended the exclusive license to the players name's, likenesses, and team logos along with likenesses.
2K tried to make All Pro Football 2K8, and while the game was alright, it didn't match up to Madden 08, first of all because of lack in features, but because it didn't even match up to the original ESPN Football 2K5, it was simply a watered down 2K football game with less features then the game previously made before it.
On top of that, 2K was in no rush to get out a yearly title, and had as much time as they wanted to put the game out, even when they had this much time, they put out a sub-par game that the few who took the time to play absolutely despised or simply played to get something different then Madden.
I'd buy Madden 2010 simply because I know what I can expect, right now I wouldn't know what to expect if 2K put out another football game, if it was as pitiful as the last one I'd have invested in nothing more then a waste of money.
for the record ---
All Pro was an "ok" game with great gameplay, the fact that you have to create all your teams according to the rules of the game, the lack of other features such as franchise, and some gameplay glitches really dragged this game into the grave.
even with that said though, All Pro had a better online league system then Madden does today, and their system actually keeps track of statistics of every aspect of the game.
if 2K could get the NFL license back, they could continue making football games, without that license though, it is completely USELESS and an utter waste of cash for Take Two to make any type of football game or for anyone to actually buy one.