Anyway, back on topic, ugh no. Replacing master chief is insanity. "Yeah, let's just replace him for the last two games, the explanation won't be convoluted at all and the fanbase will really connect with the new hero"...not.
yeah. when your goofy AI in spartan ops feels more like a person than the protagonist of the entire series, thats a problem.
No, it becomes a actual major defining element of the character himself, just like how cortana was always the more human of the two, that's THE WHOLE POINT. Which they did a masterful job of playing off of in halo 4.
so his character arch is about how little character and personality he has? AWESOME! seriously, Cortana carried the story because she had personality and played off of chiefs lack of personality, now that she's gone. well chief is kinda a non-character again.
a good way to tell if a character is well developed is to try and describe the person without saying what they look like, their occupation, or role in the story. you can't do that with master chief.
another good character exercise is to imagine them in a normal situation. how would the chief act at a resturant, how would he act at a party, how would he act shopping for groceries. how would he act on the infinity when theres no combat, he's just in the mess hall with the spartan 4's and other marines. what would he do aside from sit there?
he's all super-soldier, all duty all orders, only military. he might as well be a blank robot with no personality at all, no dialogue, just a vehicle to move from action set-piece to action set-piece. because thats pretty much what he is.
he's honestly the most empty, poorly written, and pointless protagonist of any game, movie, book, or anything i can even think of right now. outside his job and his role he is literally nothing. he's boring.
So you want to replace the chief with someone you can picture acting normal at the grocery store? Really? Sounds like you just want Halo to turn into Mass Effect