Just some thoughts
I just saw the raw of ep 13 for season 4 and by the way things are looking, it seems like there would most likely be another season for Major.
The previous seasons have all been 26 episodes each and right now the anime is still on the Bats arc without having gone into the Baseball World Cup arc of the manga.
My guess would be they might do what they did in Season 2 and split it up into the qualifiers for the Baseball World Cup being in Season 4 and if there is another season of Major, they would have it be about the Baseball World Cup.
If this were to happen then that would give enough time for the manga to carry on and eventually by 2010 they would be able to do another season.
Anyway, I have no idea, this is just me guessing. While I am happy to see more of Major, I am just hoping that it does not get draggy. So far it does not seem like much of a problem. Just have to wait and see.