The hints are about Alto surviving and Sheryl waking up. NOT about Alto coming back. (
edit:
the comments in context)
I'm happy with each viewer forming their own
interpretation of what happens, and if people interpret Kawamori's comments to mean that Alto (probably) came back.
But please don't imply that Kawamori outright
SAID or even indicated that he
definitely came back.
Because that's simply not true. "Said" and "definitely" being the operative words.