Forget the ’ what if ’ . The Volt is discontinued and was too expensive to start with and not that great of a vehicle . There is no reason for anyone to make replacement parts so the parts are not going to be any cheaper. Resale of these is terrible .
Yes, you can. All the individual cells don’t go bad at once. Volt enthusiasts (yeah, they exist!) rebuild the battery packs by replacing the bad cells from their pack with good cells from a used pack. Labor intensive, sure, but a DIY’er can and will do this. You find these folks doing this with Prius packs, and Honda Insight packs.