Not the hat!
First the crew, then Bon Clay (though I still think he's alive), then Ace…Luffy has lost so much during this arc. And now he might lose Shanks's hat too!? Oda, you are so cruel lately (but in the best way imaginable).
At least the issue of where Luffy is going to stay while he recovers is settled...maybe. I think that after he's treated by Law, his recovery process will probably take longer than usual, maybe even a few weeks. (I'd love to see Law use his powers to perform some special medical techniques.) This will give the Straw Hats (who may already be aware of what happened at Marineford) some time to get back to Sabaody. Then, Law can drop Luffy off there and the Straw Hats can finally reunite.
That is, of course, if no big surprises happen in the meantime. And since One Piece has been one surprise after another lately, that is entirely possible.