I thought the implication was clear. Tony IS DEAD and WAS CLIPPED by someone. We the audience have always seen the episodes from Tony's point of view, and the blackened silence is what Tony sees and hears when he finally gets clipped.
Remember the conversation with Bobby at the lake? "I wonder if you hear the one that gets you" - the final episode answers that question. That is why they flashed back to it at the end of last weeks episode. He never heard the one that killed him.
Curious why so many times in the show, it was made obvious to us that the characters were also hearing the music we were hearing. With soundtracks, sometimes it is just for our benefit and other times, we are merely listening in to what the characters are listening to. Chase made a point 4 times to show us that the characters were listening to the songs playing. Paulie in the airport scene turning up the oldies, Tony's fat driver blaring the hard rock and then it cuts out when he opens the door, AJ's stereo melting while Bob Dylan fades out from the heat, and then Tony picking the Journey song from the jukebox. Was this to tell us that the song ending in the final scene was ending abruptly from the perspective of Tony? Was he trying to differentiate and tell us that the songs tonight are playing for the characters, not just a track overlay like a movie score. So that when the song went silent, it was going silent for Tony?
Also, everything in that diner scene was from Tony's perspective. Watch him enter and look at the empty booth, then he looks at it again, and he's already sitting there. Did he watch himself come in the door as he did all the other characters in that scene? Was this to show us that everything from the songs, and the views of the door were from Tony's perspective? Meaning when things went dark and silent, they went that way for Tony?
Oh well, either way, great ending to a great series. I'll miss it.