Im pretty sure that locke wont replace chief in the next halo game, but it could happen in the next few games.
At first I was scared, you know? Master chief is what makes a good halo story and is what defines halo in a way. But after watching halo nightfall, I honestly wouldnt be too mad if chief was replaced by Locke. Locke is a total bad -Yoink-, he has an emotional side (from what I can tell), and is an interesting character In general.
What are your thoughts on IF 343 decides to replace chief with Locke?