It would be incredibly foolish to cut down from 24 games. The players aren't going to see their salaries cut proportionately for 19 games, and when the competition extends past 20 teams (which will happen sooner than you think), the players will want their mouths filled with gold to add more games. Aside from the match day revenue decreasing considerably, the big thing I see being an impediment to cutting the schedule is that many stadiums are locked in to having so many games each season.
In 2029 Wests are to play at least 7 in Campbelltown and 4 in Leichhardt. Square that with a 9 game home slate every other season. Less games, less inclination for new/improvements to be funded by the State too. I'm not sure how many Bears games are locked into Perth but if that is 10, then there would be no North Sydney home game and Magic would always be an away game.
I can't seeing 19 games being a goer beyond off season paper talk.