Outside of space and time is weird. Eternity is like something so long and so short that we're actually already there as we live our lives in space and time. Almost everybody reincarnates as something. I believe we choose our next cycle based on what we learnt in this one (a form of karma).
Those that reach Mok Sha, or a state of peace outside of space and time, join God at the singularity without reincarnating as anything living (which one might consider Heaven).
To put it another way, we're fated to choose and choose to be fated. Forever lasts as long as we want it to. We exist ubiquitously.