Sure, everyone is calling for Eren's name, but he doesn't have many years to live and someone will have to take his place. Eren is already worried about choosing a successor for his Attack Titan and he doesn't want any of his close friends it inherit it, even if he is strained from them. Floch is currently being painted as the closest being to a successor who is both loyal to him and not exactly a close friend. Also, for what reasons would Eren would kill Floch? If Eren is simply using Floch as a tool and will simply dispose of him, then how does that make Eren, or his successor, better than him?
The thing with Eren that bugs me, right now, is that the only thing we know is that he wants to free the Eldians from their oppression, but we are not sure if this plan involves threatening the rest world or genocide it. We don't have any idea if he has actually plan for the after.