I agree that cost might be the bigger issue here as people don't seem to be able to balance multiple LCG's, and I doubt anyone with the base game would be able to integrate it at all with an LCG core set. I would be bummed out having to invest in this new game just to get more experience out of a game I already own.
I think it's been mentioned before, but maybe in a different forum/thread, Print on Demand expansions might not work since the quality of the components would make them known to other players. It'd be nice to be able to get a new team or two from a PoD expansion, but then if you were to receive star players from the expansion it might tip off other players you have one of these cards based on it's appearence.
Honestly though, I think if it's just a whole new team it would be worth it and people might buy them. No extra mechanics or anything but new teams throughout the year might be a really good idea. The friends I recently introduced to the game really like it but were immediately asking if there were expansions with different teams. That seems to be something that people universally want.