I really think TWEWY is indeed Jupiters baby. I kept following interviews of this company (actually it is the only company I have followed through) and they really want to make a sequel. However, we have to keep in mind that SE owns the IP and the original title never sold well in Japan (in fact it bombed considering the hype and the ads the had to put out) so I am not sure.
Nothing I have said will have any effect on the decision (I think) so take it as you will. Although I wnt to say, I m ready for disappointment, I can't help it but to feel hyped, Duckroll be damned etc...
Edit: You also don't have to take my word for it. You can study the credits yourself here:
http://www.mobygames.com/game/nintendo-ds/world-ends-with-you/credits
The producer, executive Produce, a lot of the visual designers and some of the planners of the battle system is enough for me,
personally, to say that Jupiter have a bigger stake in the game than it is thought.
Also, didn't the Producer actually make a cameo in the game itself?