DQ10 may well go to the DS's successor, or even DS itself if it is still Nintendo's flagship handheld in 4 or 5 years. I think those options are as likely as Wii. I don't know if it would be good for the franchise to jump back and forth from handheld to console repeatedly.
I have no idea what Square is doing with the FF13 project, and all its parts, and have no idea whether they'll try to churn out 3 FFs again this generation or not. I really think they are overdoing this franchise, with seemingly 2 dozen spin-off and remake titles every year, and think that combined with low PS3 sales is going to make FF13 sales suffer. I mean, DQ9 could easily outsell FF13, the way things are going. Yet, I doubt Square rethinks their strategy this generation. If a FF14 comes out this generation, my bet is PS3.
As others have said, there is no KH3. There is at least one related project in the works, but even though its the soonest, the next Disney/Square mashup is some ways in the future. I think in some shape or form, this franchise will find its way onto Wii, 360 and DS. As far as "Mushroom Kingdom Hearts," I'd actually be more interested in a Nintendo/Disney mashup than a Nintendo/Square one. As long as Square is developing, make it a three-way.
"[Our former customers] are unable to find software which they WANT to play."
"The way to solve this problem lies in how to communicate what kind of games [they CAN play]."
Satoru Iwata, Nintendo President. Only slightly paraphrased.
