To me the only guy who I can think of right now who can pull it off is Hemsworth. I mean that doesn't mean he's the only one, just off the top of my head. A guy who can do both the look and the performance not that it would take a lot to perform He-Man.
However, I don't think Hemsworth would want to do it since he already has Thor. I think Hemsworth will want to do some more varied roles now inbetween Thor/Avengers like his Ron Howard biopic about the race car driver.
But to pull off He-Man you basically need a Hemsworth type. Him be buffed out and beefcake as He-Man, but just dress him down and make him look smaller as Adam. Shouldn't be too hard. Doesn't have to be a huge, gigantic change. Just make it like Clark Kent to Superman from the Richard Donner movies.
Thing is, the screenwriters don't get how to do this. They don't understand that the transformation is a crucial part of this character and why children love He-Man, Power Rangers, and many other things. I went to a Robert Rodriguez QnA once and he talked about why kids loved Power Rangers and basically he said kids as they get older, their bodies are changing (transforming) as well. And not only that, the kids in Power Rangers are people not much older than them and given super powers so the kid viewers are empowered and inspired from watching the show. With He-Man its the same thing. It's not just Prince Adam transforming into He-Man, but the kid viewers by association and they feel like and want to be He-Man.