I don't really understand the audience gets whacked theory.
I read it on Digg.
Basically, we (the viewers) got taken out of the Sopranos.
We never saw it coming, everything just went black.
This explains the conversation between Bobby & Tony in the boat (& the reason it was shown again in flashback).
It also means that we don't know what the hell happened to Tony but that that our with him time was up.