Sales will tell for sure, but from past record, console manufacturers get more success if they mostly try and follow their schedule without chasing competitors in every step.
BTW, mid-life improvements always end up being underused, as games must still be compatible with the base model, so some extra graphics power, extra non-gaming features, faster loading and higher framerate are always welcome, but any console will better have the essential things, or what the console maker thinks that will become essential, since the start.
WiiMote Plus higher precision motion tracking received minimal and almost exclusively first party SW support, and Wii missed the full use of a natural development of motion control that could have extended its life and possibly could have caused the birth of hardcore motion control gaming too, and this extra life for Wii could have allowed Ninty to plan better Wii U release, without rushing it.







