Over the past month, halo servers being tracked by gametracker seem to have been plateuing but not decreasing. On the link below, if you scroll to the right corner (after scrolling a bit), there seems to be a slight dip that occurs between 11/28 and 12/3, but it instantly returns back to normal.
https://www.gametracker.com/games/halo/
529 servers ranked by gametracker.
I thought I'd share that.
-Mandalor