Depends who comes back, if it's the future then Asari and Krogan can live for at least a thousand years or something.
During my last playthrough, I was thinking how cool it'd be for a post ME3 game to have the children of certain characters on our squad.
Like Kolyat, Jacob's child, Falere, etc.
I also thought that if it were in the past, they could bring Samara onto the squad, back when she wasn't a Justicar, in her more wild and crazy days. Who knows, maybe our protagonist and her have a daughter? Dunno.
But yeah, pre-reapers would feel pretty awkward. We're all gonna die soon, the krogan keep complaining about the genophage that's going to be possibly be cured soon, and PLEASE STOP SHOOTING THE GETH. Thanks!