If we retain our identity after we die and go to some kind of god's world / realm of happy existence, wouldn't that be like a torture being in this state for billions of years, or possibly for eternity?
In the case of 'god's world' I would expect that depends entirely on the god we're talking about. I mean, naturally some gods probably love to torture people. I'm not sure what you would do to get stuck in a place like that (or if they even exist) but it is a possibility. Then again its just as possible that whatever god is in charge would be fully aware of your particular need for change and constantly update the contents of the afterlife so that you don't go mad with boredom. I'm not sure why you have settled on torture in this case. It seems like the worst possible option.
In the case of 'realm of happy existence' I have no idea how it would earn this designation if the end result was torturous. Don't you think it would similarly update itself in order to keep you satisfied? The title itself seems to defeat the argument.
But what if somehow we don't die, and live for 100 trillion years, get to learn and experience every possibility the universe has to offer.
I don't really know that something like this would be possible. I don't think there is a limit to the experiences available in the universe, so I'm not sure how it could be reached regardless of lifespan.
Would there be some kind of limit for a conciousness to say enough is enough, in any of those cases? Then what?
I suppose if this weird hypothetical limit is reached, you just start making things up, right? There certainly isn't any limits to my imagination. How many paintings would Picasso paint if he lived forever? I'm guessing somewhere between infinity and infinity. Barring that, lets assume that artistic expression runs out at some point... are we automatically removing the ability to suicide? Seems like a pretty reasonable option if you are simply finished with the entire universe. Or are we saying that even if that did happen, you'd just be stuck? In that case, its such a highly specialized existence I really don't have a clue what I would do. I guess figuring out how to suicide would be the one factoid left in the universe to figure out and so that would become my new pursuit.