It could happen, theres even a speculation about KD joining the Lakers next year, and that includes Butler as well. While Leonard will surely sign with LA next year ( If nothings gonna make him change his mind. ) Lets just see what will happeb next year.
Los Angeles Lakers is really a damn rich team that can offer max contract for at least two superstars. Even season 2018-2019 hasn't started yet, the talks about their plan on 2019 free agency is one of the hot topics right now. Kawhi Leonard, Kevin Durant, Klay Thompson, Jimmy Butler and there are also others big names who might popped up on the lists.
I would celebrate if Butler will join Lebron, it's a good combination and they definitely have a chance against the warriors, provided that Butler
will remain healthy. He is a star of the Chicago Bulls and he was able to carry the team, imagine if he plays with Lebron.
The problem with Butler is inconsistency. Yes no doubt he is good but his explosiveness is inconsistent. But playing with Lebron, I think some adjustments will be made by him.