Luffy, Kidd and Law are portrayed as the front runners of the new generation. All 3 were bickering amongst each other, and Law reacted exactly the same towards Luffy and Kidd in that he flipped out and told them to not give him orders. He vehemently denied being Luffy's subordinate and was pissed at the idea. That happened multiple times.
Even after wanting to find out the truth of his name and being interested in the One Piece, he hated the idea of being Luffy's crewmate.
Obviously Law hasn't resigned himself to join the strawhats, at least not yet. But at the same time, he can't achieve his dream without Luffy's help. At the very least, Robin's help is a requirement. I think the idea
@Roo had that Law may challenge Luffy to a Davy Back style fight over Robin is pretty reasonable. That would be the only way he could get her to translate his poneglyphs since Luffy's not about to hand out free tickets to laugh tale to rival pirate crews, and it also allows Law to join the crew with his honor in tact when he loses. Realistically it's his only hope of achieving his dream. If he wins, he can do it on his own, and if he loses, he has to do it as a subordinate, but he still gets to achieve his dream. This would also be a great way to put their rivalry to rest in a way that makes sense for Law, rather than him just giving up.