The biggest problem I have is that only about 5 or 6 teams have a realistic shot of winning it all and about that same number have no chance at all of making the playoffs. Also under the current system you're better off being real, real bad vs mediocre.
I think you can deal with this by shortening the length of guaranteed contracts. This would create more movement of players from year to year which would give the mediocre teams more hope.
I also wouldn't mind seeing some teams being contracted. A few of these teams have nothing to offer in the way of gate attractions. Take away 4 teams, disperse the talent among the remaining teams and you'll have a better product.
See I don't think this is a problem, in any sport, how many teams are expected to win the championship any year?
People complain about parity, but most teams get their chance to shine. Look at the teams at the bottom this year:
Minnesota - was a guaranteed playoff team every year in the late 90's, early 2000's. Went to the Western Conference Finals too. They definitely had their chances
New Jersey - same as the TWolves, and they even went to the Finals twice.
Detroit - was a championship contender for several years, and even won the whole thing.
Cleveland - was a contender for the championship for the last few years.
Washington - they've had a lot of big name players come through the last 15 years, and in the last few years were able to put 3 All-Stars together.
Sacramento - they were a serious contender for the title for several years in the first half of the 2000's.
Toronto - they have had very few terrible years, pretty mediocre most of the time, ok maybe they've never had a chance

Now let's look at some of the championship contenders:
Boston - had no chance to win up until about 3 years ago.
Miami - finished last or near the bottom twice in the past decade.
New York - they were a joke for about every season over the last 10 years.
Chicago - Since '98 they had more seasons with less than 20 wins (3 - although one was a lockout) than they've had winning seasons (only 2 - up until this year).
Orlando - only been a contender the last 3 years really, pretty mediocre the rest of the time.
Dallas - before the 2000's, they were the joke of the league for what seemed like forever. Great ownership helped turn that around
San Antonio - great front office and some luck.
LAL - ok they seem to struggle the least, but they have good ownership and a good front office. They share location with a perennial cellar dweller, so I think a big part of their success goes to management/ownership.
So basically what I'm saying is, it's not the same teams at the top and bottom every year. Some of the worst teams now were actually championship contenders just a few years ago. Go back a few years and look at the standings and playoff picture, pretty different than what it is now. There's really a small number that never contend (Clippers, Memphis), and a couple that always seem contend (Mavs, Lakers, Spurs). But the teams that always suck seem to have the WORST management/ownership, while the few teams that succeed have the best management/ownership and a little luck. But even teams with terrible management in terrible locations (Detroit, Minnesota) have had chances to contend. There's tons of parity and variety in the NBA, at least more than people give it credit for.