Elle and I

at the very end, you notice how elle's name has a "?" not a "-".... and because there were rumors of Sophie being a trainer for Vernita's daughter in a possible sequal... maybe that thats just because Tarratino didn't wanna reveal the ending for vol. 2, and maybe it isn't sophie, but instead its just elle...

he told EW that the mythology of v.3 was sophie fatale would inherit bill's $ and she would raise nikki green. but he could change it as he saw fit.

The question mark is if Elle died or not. Because we dont know if she died.

Well, unlike Schroedinger's cat, people who "might" be alive at the end of a movie have a better than average chance of pulling through for the sequel. I think this is definitely one of those instances.