I'm not sure that any of those would "save" the Wii U, but some of them could certainly help more than other.
A new IP sadly isn't going to convince people who aren't already on board. It would take some big exclusive, and as cool as a new (GOOD) Crash might be, it wouldn't do it. It would have to be something like a Pokemon MMO, or FFVII remake. That level of huge.