Humans becoming domesticated by benevolent superintelligences are some of the better futures with superintelligences, in my mind. Iain M Banks' Culture series is the best depiction of this I've come across; they're kind of the utopian rendition of the phrase "all watched over by machines of loving grace". Though it's a little hard to see how we get from here to there.
What will AI find fulfilling itself? I find that to be quite a deep question.
I feel the limitations of humans are quite a feature when you think about what the experience of life would be like if you couldn’t forget or experienced things for the first time. If you already knew everything and you could achieve almost anything with zero effort. It actually sounds…insufferable.
You might find Stanislav Lem's Golem XIV worth a read, in which a what we now call an AGI shares, amongst other things, its knowledge and speculations about long-term evolution of superintelligences, in a lecture to humans, before entering the next stage itself. https://www.goodreads.com/book/show/10208493 It seems difficult to obtain an English edition these days but there is a reddit thread you might want to look into.
Honestly that part of the article and some other comments have given me the idle speculation, what if that was the solution to the, "Humans no longer feel they can meaningfully contribute to the world," issue?
Like we can satisfy the hunting and retrieval instincts of dogs by throwing a stick, surely an AI that is 10,000 times more intelligent can devise a stick-retrieval-task for humans in a way that feels like satisfying achievement and meaningful work from our perspective.
(Leaving aside the question of whether any of that is a likely or desirable outcome.)