I really hope they don’t make them brothers, with Hook or PP, but I suppose it is possible. I think one complaint people have had is slightly contrived family connections. Some are going to continue to play out naturally but tying everything back to Rumple in such a direct way gets to almost jump the shark territory (and hey they are on a boat in the ocean).
I hope this is actually just a reshoot of the scene they already planned before, and are introducing it as a way to kickoff this third season as a thematic thing. Season 1 opens with Emma’s father. Season 2 opens with Henry’s father. Season 3 opens with Rumpel’s father. I’d love it if it ends up pointing to Oz instead of NL actually. Something that has a very long payout, nothing to do with the immediate arc at all.
“If I had a world of my own, everything would be nonsense. Nothing would be what it is, because everything would be what it isn't. And contrary wise, what is, it wouldn't be. And what it wouldn't be, it would. You see?” -- Lewis Carroll, Alice's Adventures in Wonderland & Through the Looking-Glass