Maybe we'll get a 10th Anniversary Reunion movie in a few years time.....
They should have done Serenity as a D2DVD experiment instead of releasing it on the bigscreen. A modest success there may well have prompted more, much in the same way that Ark of Truth and Continuum will no doubt lead to more SG movies that go D2DVD.
Serenity definately would have done better as a d2dvd movie. I thought it was odd that they were doing a big movie when even the tv show didn't do that well.