I think b-spec and endurance races (the traditional kind) are linked now, in PD's mind. Probably because they want to make sure that we can trade spots so "bob" can do a stint. Maybe they shelved b-spec and we're not getting enduros? Or, maybe MGT's right, and we'll get it this year?
GT still has the best overall package as far as game combined with sim racer. However, we have yet to see what one company's final product will be like, so that could no longer be true, very "soon".
Personally, I'll be where my friends are, and if they keep playing GT, that's where I'll be. If they are in three games, then that's where I'll be.