I think Snow is still unaccounted for. Her shtick got old fast, IMHO, but I wouldn’t be surprised to see her show up next season at least once. She was last seen getting locked up at the Lighthouse, but there’s no reason to believe the Chronicoms would have cared to kill her, since she’s obviously not SHIELD. Or she might have been transferred to another prison, if the Lighthouse got destroyed like Izel’s temple did, (I think Simmons just said “we lost the lighthouse” so it’s unclear. It might be intact and under Chronicom control).
I’m not sure they’ll stay in that time for the whole season. They effectively have a TARDIS now. (Which Jemma, a known Whovian, had better mention at some point.) I’m assuming next season, or at least part of it, is a Quantum Leap/Evil Leaper-esque chase through time, using LMD Coulson’s knowledge to stop the Chronicoms from destroying SHIELD targets at different times in history.