Think we're good for a while there given the amount of player pushback on extending the season for just one game (and they needed to scrap a preseason game as well). Given the nature of the game it seems impossible to stretch it to 20 games or so (not that it will never happen, but we're some years away from that imo).
I think load management in the NBA is bullshit (eloquently put by Anthony Edwards as well during the All-Star break) but it's exactly because there's too many regular season games that players feel they can easily sit out games without any impact on record/seeding. If you shorten the season they'd maybe feel the need to play more games to secure a playoff spot but, like you said, too much money involved to shorten the season.