If it didn't end I don't think the NY war would have decimated the Sopranos crew, so the following include Sil, Bobby, and Tony being alive.
I would say the new NY boss and their relationship to the Sopranos.
The new guy, Walden.
Whatever happened to Artie Bucco?
Tony's eventual revenge on Bobby for the fight.
Tony's life after therapy.
Tony and Patsie's new relationship since their kids are engaged.
Would "The Aprile Curse" hit Paulie?
etc, etc, etc