From the looks of it, I guess Law will be going with them on the same ship. I'm wondering where his comrades are. I'm secretly hoping that they are dead, and Law is after kaidou for revenge (eventually joining Luffy's gang), but I don't think that is the case.
Oh, and am I the only one who teared up a bit at the kids wanting to say goodbye.
Hmmmm, I don't think that a fight with Doflamingo will happen anytime soon, nor Law joining Luffy's crew. If I'm not mistaken, at the very start of the series, Luffy said he will gather 10 crew members (correct me if mistaken) and become the King of Pirates, plus they have Chopper as a doctor. Jimbei will probably be the 9th crew member when he finishes his business with Fishman Island. Regarding the fight with Doflamingo, I don't think it will happen because Luffy's gang is quite messed up with Big Mom after Fishman Arc, and a fight with a Warlord might be too much.