Technically, LeBron can go to any othre team but realistically is just a few that have the cap space to accommodate what will likely be the largest salary ever. Philadelphia would have top get rid of several player top make room since it has several players that will be coming off their low rookie contracts and demanding top money; Embiid already has gotten a new contract and Simmons is next along with some key player like Redick that have high dollar contracts. Golden State has the highest payroll and Durant will be getting much larger contract than the $24M he gets now and after next season Klay Thompson is up and he will also be getting considerably more than the $18M he gets that could be considered a bargain and if he decides to leave, he would the the top player for a lot of other teams instead of the third wheel after Curry and Durant The same is true for many team and only a few have the cap space to take on LeBron and the supporting cast he will demand. LA has the cap space and the Knicks can shed a lot of contracts and have money to sign LeBron and another big name to go with Porzingis to create a contender, particularly in the weaker East Division.
Also, there is the chemistry aspect. Kyrie went o Boston because he did not want toi play with LeBron and if he were to sign with Boston, Kyrie likely is gone. I saw someone mentioned Milwaukee but I am not sure LeBron and the Greek Freak would be a good match, particularly when many consider him the next best player in the League and would be in direct competition with LeBron; it might be the same case with Houston and Harden plus Houston might not have the cap room because resigning Paul and Capela will not be cheap. Lebron does not just move to another team, he takes over the team and demands players he likes and even new coaches, something that does not sit well with most players or GMs.
Lebron will be 34 next December so he is getting to the end of his career and, much like Kobe, he started right after high school and played high minutes everywhere he has been so he has a lot more miles than other players his age. Realistically he has 3-5 year left, probably closer to 3, and with the current make up of the League his chances of catching Jordan title-wise are pretty slim, so my guess is he want to end his career in one of the bigger markets with an eye on his future after basketball and LA is without a doubt the place and the fact the he bought a second mansion there would appear to indicate he will be living there after he is done playing; I understand he spends a fair amount of the off season there already. LA has the cap space and few young promising players already and if it can get George and Leonard then it has the core for a real contender.