User blog comment:RoyallyBella/Official Season 7 discussion blog/@comment-25830140-20160422221050/@comment-2056915-20160424023424

Nabu's return would make sense if they let him in season 5. Not now or later. It would make the story line become complicated.

Riven may return... Well, I hope.

In the comics, Musa and Aisha all have new love(s) so it is possible that they are following the trend in the animated series.