As we have seen from the manga and anime. Laws major Plan is to take out one of the Yonko. Who do you think they are going to take down?
Me personally I doubt that they will try to take down shanks or Blackbeard. the reason why i think they won't take out shanks is because of the friendship they have luffy has never been a person to break a friendship. Shanks doesn't look like he would break a friendship either. As we seen luffy would RATHER NOT fight his friends. Luffy already stated that he doesn't care if he has too take down shanks BUT I don't think shanks can become the pirate king so I highly doubt that shanks will fight for his position as YONKOU.
Blackbeard:Because it seems to me that Blackbeard and luffy have a rivalry going on. They are very similar in personalities and goals. I feel like Blackbeard will be the last step luffy has to pass before becoming pirate king.
So we have to YONKOU left BIG MAM (MOM) or KAIDO of 1000 beasts
Two big players and we have yet to see full face and powers...
I personally think that they will fight Kaido because it has been seen that SPOILER ALERT FOR ANIME ONLY WATCHERS
Who do you think it will be?