Dont get your hopes up to high. Com's cutscene graphics were an abosolute miracle on the GBA, and they were all 20 seconds at the most. Yes, the DS should be able to handle PS2 level graphics for cutscenes assuming Sqare Enix is going to push the limits once again. But on the gameplay, it couldnt get farther then say, Dragon Quest IX graphics.
none of this is true at alll....there are at least 8-9 games from square enix set for nintendo systems, they're better buddies then sony sometimes. 2ndly, if they made a portable Nintendo-FF deal, Crisis Core and Dissaidia would go against that