IMO I think it will die not because of the users, but probably if the miners forfeit mining.
You realize that mining difficulty will adjust downwards if many miners stopped mining, resulting in the remaining miners starting to profit again.
Even when there are no more block rewards there will always be mining as long as users keep making transactions with non-zero transaction fees.
There are so many people out there that do not understand the reason for the cap fo Bitcoin being at 2.15 million (not sure if that is correct). The cap is there because the developers have already anticipated the lifespan of Bitcoin know by placing a cap on the project, they will ensure the life of Bitcoin for some time to come. I did not know that if miners stop the difficulty will go down? That does not add up to me though. Please explain further on that.