Could this have been a movie-theater ad? This makes little sense as a television ad (sounds like it would’ve been too long, for one) but it actually sounds plausible as an in-theater ad, which can be longer and more cinematic/artsy/abstract.
This is what I was thinking. In fact didn’t Coke do a series of in-theater ads that were like student films or something? Even so, if it existed you’d think it wouldn’t be that hard to find.
Or, a shameless style ad in the movie itself. (There are several that do show the protagonists drinking from a can with a logo with no shame) This could be a case where the OP confuses an ad on screen with a similar plot with the characters or character being dead.
An example: Just Like Heaven (2005) where one protagonist that thought at first that the girl was dead in the accident, but figures out that the girl is not dead but in a comma and in the scene drinks from a diet coke can to cool down before explaining it to investigators or friends.
(Cooling down with a diet coke bit at the 1:00 minute mark:)
As I have seen from previous cases of movie or ad identification, our minds on several occasions do jumble our memories, particularly the ones that are not deemed crucial. It would not surprise me that with a movie that mentions “heaven” a memory can then create a sequence from entertainment media that was not really there, but a composite.
It is like with the “alternative ending of Big”. It is more probable that some movie sites mentioned and showed clips of the many copycat or earlier movies with the same or similar premise and one where the girl did decide to join the hero to become a little girl in school got confused by many as being the mythical alternate ending of the movie.
On Edit: or not, as it seems the OP has identified something.
Holy shit, I just found it.
It’s for Pepsi, not Coca Cola.
Dammit, the last 10 seconds or so are not on the damn video. They go in the theater, and the audience is all angels who turn around while sitting in their seats and greet them, and then the character (I don’t know which one) says “So, this is Heaven?”
No date is given, but I know it had to be 2003.
I am the motherfuckin man 
Here is the complete spec ad, from the people that made it:
Thanks, Czarcasm!
This is one of those commercials you can watch 50 times. And when you do, observe that the commercial contains a series of circular images (the lone cheerio left in his bowl, his dog’s feeding bowl, the keychain ring that flies through the air, the washers he makes at the factory, the soda cups seen from above, etc). And I just figured out why:
It symbolically foreshadows a) the 0-ness of dying and having 0 life left and b) the halos they get at the end.
Czarcasm is the man too, but so am I
PS: my memory of this very memorable ad was almost perfect, except for one thing:
I had embellished the end part in such a way that the people in the theater had angel wings. But now I see that they do not. Only the guy at the door to the theater does.
But dammit, they should, it would be cooler that way.
Heh, called it.
Now there is another question: Since this is a spec commercial, where did you see it?
I’ve been mulling that one, too.
Either a) they played it at the movies or b) I saw it on tv, meaning it did make it to television. But if I saw it on TV, I bet it was a shortened version, 30 secs or so.
Damn! That is pretty much as horrifying as you described it @Something. Sorry to doubt you.
Here’s a McDonald’s commercial that ends with a husband using a seamonster to murder his nagging shrew of a wife:
Also, in the 1930s the Disney Corporation allowed a newspaper strip to show Mickey Mouse attempting suicide multiple, multiple, multiple times:
Nationwide had that dark ad where the dead kid talks about everything he missed.
As for this Pepsi ad, I’d swear that’s Jack Riley, character actor and Newhart stalwart, playing gramps, but I can’t prove it.
When I watched the video just now and gramps came on, I was like “Hey!, is that Stan Lee?” Alas, it was not to be. 
My favorite “not an ad” was the Mercedes “ad” made by German film students:
OK, that’s funny.
If we’re going symbology here, I think of the circle representing eternity/infinity or cyclicity rather than 0-ness.
I have a friend who has a colostomy bag. He was in an accident that ruptured his intestines… not dead, just a semi-colon.
Okay that’s pretty genius.
Hold still, this may sting a bit…