Personally, this question has me clueless, I have no idea. I have a hunch that its some one we haven't met yet, but there's the faintest of possibilities that it could be Hagrid, but I don't think so.
Okay, this probably sounds dumb, but this is why I don't think its Hagrid.

Hagrid the "prince?" I dunno, but I think if hagrid would have any royalty, he'd be a KING! He's so huge, and the title prince just dosn't carry with that... *sigh* I'm not making any sense aren't I? There's absolutely nothing to back my claims, its just my personal feeling. The prince is going to be younger than Hagrid and others, that's my prediction. I know it dosn't make sense, but it's what I think.
Sorry, this was kinda a waste of reading.