So SE has stated their priority as:
Ninja -> Samurai -> (if I remember right) Summoner.
I am trying to remember if #3 is summoner or red mage...

Outside of this list...
I hear a lot that dancer DPS is too low for the buff it gives. The invulnerability for dark knight is poorly designed due to needing healers to be ready for it and able to heal you up to 100%, and I hear Astrologian has bad MP management.

Then I just heard that every class except maybe black mage “feels wrong”...

If these concerns are correct then despite Shadowbringers 5.0 having the best story so far for any FF game, will this expac go down as a failure due to the class designs and /!or story content in 5.x (I dread 5.x being just Xenos part 2 in a half made Garlean city...)

That said...

I think SE’s priority list is right, with the exception of AST MP needing to be on the list sooner rather than later.

I thin Dancer is actually where it should be because they meed to lower its popularity... BUT this might still fail as frankly... it has one of the best playstyles right now. Is just packed full of fun. Gunbreaker is in the same position but a vocal segment is livid over the sound effects being too good, wanting them to return to sounding like a 1980s infomercial slicing tomatoes and tin cans...

Me... I would set it as Ninja -> Summoner -> Astrologian -> Samurai -> Dark Knight and not come back to dancer or gunbreaker until 6.0...