If Magnus ever joins the WWE, the he is destined to be the top face. He has the ring skills, mic skills, larger than life charisma, is tall and big/ripped and marketable face that WWE loves so much, and he's just 25 years old. I can't name a single guy in WWE that is even remotely as talented as him at his age, everybody has one weakness or another (be it presentation or talentwise) while this guy is literally made for TV. He makes all youngsters, WWE and TNA alike, look like amateurs who should be in OVW/FCW.
As for the guys already in WWE, Ryback seems to be the guy who WWE wants to put near that position right now, although he's more of a Batista instead of Cena-Type guy. Daniel Bryan will most likely become this generations Piper, the heel that is over as anybody else, or become a loveable top 3 face. It's hard too really pick a top guy within the roster right now, maybe there's some gems in the jobber division that we never could see, who knows what some guys with a good direction and a working character could do.
Ryback would be fine in a Batista role. Not sure if he has the charisma that Batista displayed near the end of his run, though.
Anyways, as for Magnus:
Yes! I mentioned him as well.
Without a doubt, one of THE best performers right now, given his age. He quite easily blows away all other candidates.
Now, could he be THE top face in WWE: Maybe not?
It's because he is British. I see that as a prohibiter of him being the top face.