the new main character should be female. That's the one thing NIS has yet to fully explore for a main console Disgaea (without being shoehorned as some DLC main character).
and it should involve Celestia more (antagonists/rivals). Earth should take a backseat this time. They could invent many new interesting classes/units from Celestia.
No. They can go make another game for a female MC, But not in Disgaea.
While I don't completely agree with more Celestia, I do think they need to NOT make the secret plot twist be about an evil human or about the Human World. They've pulled that plot twist twice in a row now.
I wouldn't mind it taking place on a human world though, atleast partially. More exotic locations perhaps. I was so happy that we got to go to the Moon in D4, mainly because it seemed so different. Also, more Aliens. I want to know more about that.
Coincidentally, does anybody else think a direct sequel for Disgaea 4 could be workable? It seems to me they might've hinted at it with the "Most Want Criminals In the Universe" bit. Although that could've just been a one-off joke... it's hard to tell with Disgaea.