I think it's fair to assume that the chances of LeBron running into a serious injury with an extended recovery time does increase as he ages. For example, I would not expect him to recovery quickly from a popped Achilles or a freak ACL injury at age 37. There is nothing anyone can do about that. But that chance is always there to some extent with any player, as Celtics fans are painfully aware.
Barring such an injury, however, I'm with
@HomeRunBaker in feeling that LeBron will likely continue to be elite for at least a couple of more seasons, and possibly longer.