Got my copy of the game today. Those generic players aren't placeholder. Stockton, Malone, Hornacek, Russell, and Keefe are the only Jazz men from those classic teams in the game. They actually have listings for the 96-97 and 97-98 teams, but the rosters are identical.
Most of the classic teams in the game are like that, actually. Even the most complete classic teams in the game (the 91-92 Bulls and 94-95 Bulls) still have two placeholders. The bigger disappointment for me is that you can only use these teams in exhibition play. They have a whole mode called "Jordan Challenge", where you're tasked to recreate a historic moment from Jordan's career. Two of these challenges feature the classic Jazz squads, but there's no option to change history.
But for me, that's just a minor gripe. I always get a ton of replay value out of 2K's online modes, and with all the work they've done to the My Player and Online Team-Up stuff this year, I'll probably be putting in a lot of time with it this year as well.
The game is super polished, and nothing like the turbo-charged dunkfest that EA's basketball offerings have been the past 7 or 8 years.