Because of this league's complexity, it's very well possible that we don't find 30 dedicated people with decent CBA knowledge and the right attitude. (The latter includes forgiveness towards fixing mathematical blunders on the go, as well as genuine interest in learning how contracts can be constructed under the Gilbert Arenas rule.)
More importantly, we really need all participants to be responsible for their franchise's future in the long term, especially in case of teams under the salary cap. Let me explain based on an example: whoever gets the Bobcats or the Hornets must embrace the rebuilding process by investing in young players, wisely using his draft picks for a year or two, and then slowly improving in season 2 or 3 (OKC too were the worst team in this league once, y'know). The worst thing that could happen to our game is some win-oriented kid with little respect for how the NBA really functions, who starts off by overpaying a couple of aging losers and then quits after a month, while complaining about Kemba's struggles in the +/- category.
Going further, since the league will focus strongly on contract construction and such, it's very possible that managing teams like the Lakers or the Bulls - with their rotations fixed and their salaries just under the hard cap - will be less exciting (and surely less time-consuming).
All this leads me to a conclusion that maybe it makes sense to have two teams assigned to every GM: one in each conference. Preferably, one would contend and the other in the middle of a painful rebuilding, so that you can enjoy the ins & outs of both processes. Practical changes would include the yearly fee rising to $4, and of course transfer ban between your two franchises.