But ultimately, when dealing with a fictional story, all that happens is what we are told happens.  We do NOT see Tony die.  Period!  Speculating what happens the millisecond after the story stops is all well and good but it is NOT what happened in the story.

One of my two favorite movies of all time is Butch Cassidy and the Sundance Kid.  If you haven't seen it, rent it immediately.  If you have you will understand what I am about to say. (Spoiler)

They don't die at the end.  They just don't.  It may be impossible to imagine them living but the movie clearly stops with them alive.  There is a reason for that kind of artistic choice.

Does anyone really think David Chase (Sopranos creator) chose to end the 80+ hours of one of the most intensely watched series EVER by conveying one of the most dominant 20th century American fiction died but he just didn't get around to showing it?

The point of the damn ending is that you figure out what you think happened.   Chase clearly didn't feel the desire or need to kill Tony or he would have killed him.  Nothing was stopping him.

Personally, I think the ending suggested life went on for Tony and his immediate family which is what I always understood the series to be about.  The daily mundane life of a suburban dad, wife and kids where the dad just happens to be a mob boss.  The final scene was clearly meant to be a typical all-American slice of life.  Something any of us might do with our families to celebrate a special occasion.  Why people need to insert a murdering gunman who was not shown in the scene into it says a lot more about them than Chase's script.