How long with LeBron overpower the NBA?

Throughout all of Lebron James' career, he has been considered one of the best players in the NBA, if not the best. The past couple years, he has clearly proven that he is the best player in the NBA, but how long will his overpowering stardom last? There aren't many challengers to his  reign, but there are a few. These few players will hope to challenge LeBron's rank as the best player in the league.

The few players that can try to overthrow LeBron are young stars, Kyrie Irving, Kevin Durant, James Harden, Stephen Curry, and Derrick Rose. A few players who are in their prime such as Chris Paul, Dwight Howard, and Carmelo Anthony could potentially overthrow LeBron. They will all try to overthrow him, but will King James allow it? The question is when will LeBron be taken over? Will he keep progressing, season after season, in the case where he will be the best player until he retires, or will he regress and get overthrown in his 30's, if he is out of his prime. The chase after LeBron is on, especially after winning two straight NBA Championships. Who will catch him, and when will it be?