Keller will be the starter... the interesting question will be who makes the roster out of Sims, Clay and Egnew. Really, I think the battle comes down to Clay or Egnew. Sims will probably make the team as a blocking tight end.
I think Clay is pretty safe, given what we've heard about how Miami wants to run their offense. If they don't want to run a lot of traditional I-formation sets with a true fullback, Clay is going to have to be that guy.
Unless he flops I think he's safe.
I really think Egnew is competing against himself. If he plays well, he'll make it as a 4th TE. If he doesn't, Miami might carry a 6th WR instead.