I would guess we'll see some 1 or 2 new songs of some old 'favorites'. Minuet, Minne, Requiem, March, Madrigal, Paeon, Elegy, Ballad, Etudes.
Ballad - I think is almost certain because I think Refresh II is almost certain for RDM, and we need something to keep up. Another possibility is a level 76+ ballad instrument perhaps (I'm guessing just +1)
+3 instruments might be nice 76+ too.
I'd really like to see a Lullaby II spell which lasts ~60s or so.
I'm guessing the 999 cap on a attack will get removed (pretty sure that exists).
A song that could induce bind or gravity or something new or unique would be nice.