It's amazing what the Miami Heat have done so far in the three years they have been together. You have to go back to the 1996-98 Chicago Bulls to find a 3-time Conference Champion in the Eastern Conference, back to the 2000-02 LA Lakers to find a 3-time Conference Champion in the NBA.
Lebron James turned in his best season, they are averaging 61 wins per season through three (by winning percentage since they played 66 games last year). They have 1 NBA Championship and could win another one before this season ends. Indiana presented some unique challenges to the Miami Heat because of their lack of strong interior play. They made Roy Hibbert look like Shaquille O'Neal and that worries me when they face Tim Duncan. But if they pull this off, get their third title in franchise history (and since 2005-06), they will tie themselves with the Phialdelphia 76ers, Golden State Warriors, and Detroit Pistons for 5th-best all-time.
All in all, I think if they win this title, we can call Lebron's tenure in Miami a success. If they lose, they will have something to prove next season. Remember, Danny Granger and Derrick Rose will be back next season. Teams like Washington (John Wall, Bradley Beal, Emeka Okafor, Nene, #3 overall pick) and Cleveland (Kyrie Irving, #1 overall pick, Dion Waiters, Tristan Thompson) look to be much improved next season. Remember, Detroit and Atlanta have deep pockets this summer to reshape their rosters. Brooklyn is a year older. And new salary cap restrictions will be put in place before the beginning of next season (the graduated Luxury Tax) that will affect the Miami Heat's roster. Dwyane Wade looks old and has had 2 straight postseasons with knee injuries that have limited his effectiveness.
Out west, San Antonio and Memphis may not be a threat, but Russell Westbrook will be back. Dwight Howard and Chris Paul will be free agents, possibly changing the outcome in the Western Conference. My point to all this is that Miami may not have as clear of a shot at the second NBA title with Lebron next season as they have right now. That will be great from a competitive standpoint, but not from the Heat's point-of-view.
Here's hoping they beat Duncan's Spurs, who have never lost in the NBA Finals.