I have a hard time seeing it happen. While Law likes to act all aloof and cool. He gets caught up in the SH behavior and, at least to me, it seems like he enjoys the company even though he might hate that he does. Ntm he also has that huge debt of taking down Doffy for him. At the most I see Law becoming a friendly competitor for the One Piece but I still think he will either die or save Luffy with his operation. It would be a great end to his character arc. Instead of destroying everything before he dies, he dies in the act of giving life.
it wont happen, they will not betrayed them. i bet for it.
when in PH robin told luffy about that. maybe she have been experience with that, remember she always betraying each secret agent that she working for. so it's just remind of luffy just be careful on him.
As of now... i dont see Law THAT bonded to Luffy as a friend (even if He saved luffy's life and Luffy killed Doffy for him) .... i may be wrong cuz maybe its just his way of living... like "hard on outside, soft on the inside" and has real friendly feelings for Luffy...
But in case of a betrayal, Luffy will win Law's trust again am sure :) there'll be no fight