The instant that you say eternal... I think nightmare. I don't care what you call it. Doing anything over and over again FOREVER would either have to involve an endless reset button or the brain capacity of a slug.
My guess... eternal doesn't mean unending, in fact I think the endings are exactly what makes eternity tolerable.
Think different consciousness -- you can read about about different states of consciousness even if you haven't experienced any of those -- which can include timelessness, transcendence, europhia, altered consciousness -- just as reported in accounts from diverse cultures/viewpoints/individuals (from around the world).
So, it's only factual that different states of mind that aren't like those we all normally have do exist.
For me, that's not only a theory, as I've
personally experienced some different states of mind that are unusual due to things like Transcendental Meditation, and other ways. So, it's only
factual that altered states of consciousness exist. (it's not a hypothesis, but a fact)
Ergo, logically then, timelessness, and very many new and higher experiences (states of mind, new types of music, arts, interactions, and so on) are the
least to expect in a better and longer life. Based even on what I've already experienced, I can see that far more is possible for consciousness. Ergo, multiply that by hundreds of millions or even billions of unique individuals contributing, and the possibilities become practically endless in that having experienced thousands of good experiences, I very likely would like to come back to some and do them again, and so we could expect combinations and permutations even of already known things, in addition to new things. (Another interesting consideration is a very literal translation of wording in the bible refers to an
"age to come" which suggests (my speculation) perhaps something of very long but finite duration, like say the duration of a given universe within certain conditions that are advantageous (until that universe needs replacing), and then there would be a change (perhaps to another new subsequent 'age to come' after that one, one might wonder).