The 2015 playoffs were as big a departure from the norm as I can recall at any point in my life. No Lakers, Knicks, Heat, Pistons, or Thunder plus the Spurs and Celtics were gone by round 2. The Celtics weren't expected to go far this early in their rebuilding, anyway, and the Knicks/Lakers have almost been condemned to failure for a few years running. However, I meant this as more of a big picture thing from a historical perspective in that it was shocking to see the absence of such a large group of teams whose collective all time success has basically blanketed the NBA from its very inception to present:
1949-54: Minneapolis Lakers dynasty where they won every NBA championship except for 1951
1957-69: Red Auerbach, Bill Russell, and Bob Cousy's unprecedented and unmatched 8-peat which extended to 11 titles in 13 years. Cousy retired following the '63 championship series but was widely considered the Jordan of his day due to his versatility and superb ball handling skills so he needs to be included despite missing the final five titles.
1970-79: A free-for-all during the NBA's closest brush with actual parity. The Knicks and Celtics were the closest any team came to legitimate dominance but each only won two titles during this period (Knicks in '70 and '73, Celtics in '74 and '76.) Despite the lack of a clear cut alpha, there was definitely a theme of business as usual since the '70, '72, and '73 NBA championship series were all Lakers/Knicks pairings and the Supersonics and Bullets faced off in consecutive seasons from 1978-79. There was a virtual army of repeat NBA finalists during this stretch with the Bullets appearing 4 times, the Lakers and Knicks 3 times each, and the Bucks, Supersonics, and Celtics twice each.
1980-88: Magic and Bird tell the rest of the NBA to fuck off. Dr. J and Moses Malone's 1983 "Fo, fo, fo!" team is the only thing interrupting a potential 2-team 9-peat.
1989-2002: Age of the repeat offender. This actually extends back to the last 2 years of the previous era with the '87-'88 Laker title teams. Aside from the '99 Spurs, we had a 16-year stretch where no team could win without repeating or even 3-peating. Interestingly enough, every champion from '89-99 had never won before this era.
2003-2015: VIP Party. Aside from the Mavs and Warriors, every team to have won during this time frame had either won in a previous era or would go on to win multiple titles during this era and the Warriors may join the rest in the near future so it's really too early to judge on their status.
With that back story established, it seems like the NBA has its most legitimate shot at not being a good ol' boys club in league history. The east is a crap shoot and will likely remain as such for at least 2-3 years. The Spurs can't realistically be counted out in any season until they finally fuck things up for themselves and that hasn't happened yet. In fact, the last two times they've had a losing season, they've literally improved by 35 and 36 games the following seasons respectively (1988-89 they went 21-61 followed by 56-26 in 1989-90; 1996-97 they went 20-62 followed by another 56-26 comeback year in 1997-98; these two comeback years were also the rookie seasons of David Robinson and Tim Duncan.)
The Thunder have a lot of unknowns between the arrival of a new coach, the uncertainty of whether or not Kevin Durant will re-sign, and also if Russell Westbrook's emergence as a powerhouse will work for them or create confusion as to how their offense is gonna run with a healthy Durant back in the lineup. After narrowly missing the playoffs, they'll be hungry as fuck this year for sure though, that's beyond obvious.
The Lakers are already rumored to be after Dwyane Wade and Demarcus Cousins. Not sure if they have the cap flexibility to land both or if they even intend on landing both if either of the two is landed. Kobe and Peyton Manning seem to have a lot in common right now with both being all time greats in their twilight, fighting through major health issues, and being far too determined to let anyone other than themselves make the call for them as to when it's all over for good.
The Mavs almost seem to be a long swan song for Dirk as a sign of gratitude from Mark Cuban. He's not quite washed up yet but has definitely lost a step and they don't seem poised to do anything better than maintain the status quo given the fact that Rondo is their biggest free agent acquisition in years and he's not even a true top tier player as of the last couple seasons.
This analysis all really hints at teams like the Warriors, Grizzlies, Rockets, Blazers, and Clippers forming the western conference's playoff nucleus for the next 5-7 years with teams like the Spurs, Thunder, and Pelicans filling out the remaining spots more times than not.