In an interview, Kaz confirmed there would be private rooms. I'm assuming there won't be restricted events like in GT5P, i'm thinking a completely customisable game like you said, with lap numbers, circuit, tyre restrictions, car type restrictions, all decided by the host.
Thats what i want anyway, and PD always seem to deliver
They have seen how big the online community is with GT5P, the last thing PD wants to do is release a game with disappointing online features, especially when almost all of their competitors have good online play.