After reading the link Cocomo posted I don't think there's any doubt - Tony was dead. The cut to black was the final change in POV that the director performed repeatedly in that scene (normally you as Tony got to see who came through the door but when you cease to exist in that moment...)
The amount of foreshadowing and length to which the whole series was self-aware and directed to this purposeful ending are absolutely amazing upon more reflection. I thought the Sopranos was an all time great series before reading through the linked reference... I think it is ten times more impressive for the discipline and layered consistency David Chase carried through the series after reading the link. And if you missed the link mentioned here it is again: LINK
There are four pages of long analysis of the show in that link... they flew by for me... and my god I loved even some of the smaller moments they went back and pointed out like: seven souls montage from opening episode of last season
Don't just go to the second youtube link and expect to fully understand to significance of the references on teh first listen (although you should be struck about the subject of death and how each of the characters referenced would apply to Tony correctly were the ending of the last season to show Tony's passing).
The discussion of the Men's Room references, the Lincoln references, the Godfather references (how young Pacino began his descent by killing after emerging from the men's room), the resemblance between the MOJ wearing man in the final scene to Tony's father, the significance of the member's only jacketed men in the series, the 2001 shifts in POV, the Orange cat (Adriana's spirit), and even the Magic Bullet song which probably deliberately referenced the Magic Bullet that killed Kennedy made for some very fun reading. I probably didn't need to be convinced after the first page of the blog, but still enjoyed reading more and more (and more)