Heya! Sorry for the late reply, got caught up in some menu designs for my other game.
Yeap! You'll be able to continue playing until you "choose" an ending. The plan is that on higher levels, you will be able to select endings that involve more people once the higher mind rooms are introduced! The next update will add in Elaine's and Kay's personal ending, so it might be a better idea on what personal endings will be like!