But also I can't see Greg getting away with it either. Portia put it together (with Tanya), and I assume Tanya was supposed to die in a way that made it look like an accident (although...not sure what they thought with that bag of villan shit...duct tape, rope, etc).

I'd think that a yacht full of people with bullet holes in them will dead that real quick - plus you have the picture of Greg in Quentin's house. Seems like it'll tie back to him. Portia got the hell out of dodge, and maybe she doesn't want to mess around with the Italian mafia, but there are at least 5 loose ends - Greg, Portia, Jack, and the dudes who stayed behind/jumped off the boat.