I'm not taking requests, I was quoting a couple of posts that Goblinboy made on the Yahoo AIF group.
As you can see from those quotes, while an expansion to SD3 is *possible*, it's not certain and it's definitely not going to happen soon. And a sequel to SD3 is almost certainly not going to happen at all.
The main limitations to any expansion to SD3 are the amount of work involved (and some of the suggestions that were made on the AIF group would involve a *lot* of work, eg. having Yuki at the party), and the effect on "game structure, dynamic and theme".
Hope that makes sense. And as always, if you have any feedback on the game please send it to Goblinboy. I'm sure he'd be very happy to know that you think it's the best game ever, but if you only post it here I doubt he'd ever read it.