Honestly, I think this would be a great landing spot for KD next summer. People will speculate the Lakers but if KD really wants to try and prove he's the best in the NBA, then joining Lebron and being the #2 on a team where Lebron is #1 won't cut it. Also, he got KILLED for joining the 73-win Warriors team and is consistently getting called a "snake", "soft", etc. Now imagine if he teamed up with Lebron, that'd kill his reputation for good.
The difference with AD joining Lebron is that AD would join by trade, not FA (so it's not AD's decision whereas KD has his own choice to make)
I think there's actually a chance Kawhi decides to stay with TOR, but KD could go to the Knicks or Clippers (if he does leave GSW).