I really doubt it'll be a TP sequel... and really, I hope it isn't. I hope it's something that takes place before TP. I wouldn't be disappointed if it was on the TWW side, either... that'd be neat.
I really don't know where he'll be from. Rumors state that it's OoT!Link. If that's the case, then we already know his origins. However, if it's a different Link, I'm hoping they'll be rid of the whole forest bit. I'd like to go back to living in a HOUSE or something. I don't want him to be some stranger from the forest. I'm hoping they'll make him just another normal boy living somewhere in Hyrule. Maybe in a small town outside of Hyrule, or even in Kakariko Village.
Or maybe they'll stick with the water thing and he'll be born on a BOAT! Arrrrr me matey!