If neither the Cavaliers or the Spurs make it to the finals this year, LeBron will go to the Spurs to play under Coach “Pop” with Kawhi Leonard and Lamarcus Aldridge, as the next big 3. Patty Mills and/or Isaiah Thomas will play point guard. There will also be a couple of strong 3 point shooters, such as Kevin Love or Kyle Korver, and some young up-and-comers with high level 3-point shooting skills and some defensive chops. A deep bench will include many of the present Spurs players.
*If Leonard should decide to not re-sign with the Spurs (unlikely) LeBron and Leonard will go to the same team. The only alternative to all of this is if LeBron gets together with Anthony Davis. But, the Spurs scenario is my base case.