It's too early to tell yet, but in the end I think it will end up being Asiata and Bushrod starting. While I'm not high on Bushrod's run blocking, I am impressed with his dependability. He played hurt all season as our OL were dropping like flies. Gase knows he can depend on Bushrod to show up and protect Tannehill, which is why he had him paid to come back.
Larsen has some physical ability, but despite his veteran status, he still has some holes in his game. He has a strong anchor against bull rushes in pass protection, and quick feet, but he doesn't generate push consistently in the run game. He also has difficulty locating and striking his target when in space. While Asiata is a people mover, he also isn't the best at locating and striking his target in space. Luckily, the Dolphins have Pouncey, who if healthy, is extremely good at locating and striking his target in space ... and has the speed to get there. In fact, I'd say that's Mike Pouncey's greatest strength.
Having those same drawbacks in space is part of the reason I doubt we'll see both Asiata and Larsen start. Bushrod is a little different player, and obviously Gase likes what he offers--stability in pass protection and dependability over the course of the season. So, I'm guessing that leaves one spot, LG, for Asiata and Larsen to battle it out. Then Urbik and Larsen look to be our interior subs with the rookie Smith having a real shot to make the roster ... but probably at the expense of Anthony Steen.
Mind you, it's early, there are no pads yet, and the two rookies need time to learn, practice and reps to show what they can do. This is a process, and I doubt anything is set until the 3rd pre-season game ... so look for a lot of positional shuffling and coachspeak dis-information until then.