Well, since Mattel is sticking with the "He-Men through the Ages" concept, they might as well go all the way with it!!
So NA He-Man might as well be a "different" He-Man, and not Adam traveling to the future.
Then you could also say that Dolph was a different He-Man too, and have the movie actually tie in to the canon in a better way instead of the cop-out that too many of us received the 1987 movie to be.
So . . .
That way, you could frame things around a timeline based on our own actual time.
Say Preternia (Wun-Dar) is thousands and thousands of years ago to us, and then Adam is thousands of years after that (yeah, I'm TOTALLY ignoring Mattel's "Wun-Dar was 100 years before Adam" nonsense).
But Adam is still in "our" distant past, whereas Dolph would be 1987 just as the movie depicts our own Earth, and then NA He-Man would be far into the future from now.
That could be kinda cool . . .