A thousand years at LEAST. People can sink decades into WoW, think about what games will be in a hundred years -- right now we have technology that automates forests, but when we get proper AI, games could have content enough for a thousand years of playtime - or more. All the art, all the literature (old and new), video games, movies, professions, sports, locations, planets, galaxies, multiverses, foods, people, activities.... I can think of things to keep me occupied for a few thousand years in a minute, and I have no clue what the future will bring. "Boredom" is just a crappy coping mechanism. Nobody who understands what death and life are goes "oh welp, I guess I'd just rather not-exist right now" because they're "bored."
Games, in fact, would probably be enough to keep anyone occupied for a ridiculously long time, once we reach the point where we can feel what's in the game and see it as it were real - then only imagination is the limit and we can experience anything.
