According to
JJ20X on Forumbox the tier codes for MTV HD, now the free period has ended, are the same as the SD version.
So there's nothing stopping the SD versions of Channel 5, Paramount, Comedy Central and MTV being removed, they've already swapped their EPG positions.
Space for another ViacomCBS channel to launch in HD maybe. They still have those apps to launch, the ones mentioned last year when their deal was renewed. My5, Pluto TV and an MTV one if I remember correctly.