The Last of Us studio has multiple single-player titles in development…
Information originally from MinnMax's Ben Hanson. There is an existing game used to describe this new game to Hanson as a point of reference, and all we know is that that game is not Hitman.
I wish TLoU 1 gave you the option to sacrifice Ellie. Have an alternate ending where they find a vaccine and everyone lives happily ever after (except Ellie).