I would rather Square figure out how to make an awesome HD RPG than a handheld entry that would probably be similar to a lot of games I've already played. I think they realize this, given how Dragon Quest has slowly crawled back to consoles (and Sony) since taking a chance with DQIX.
The next FF would be more likely to go mobile, as that's where Japan is right now. 3DS support is in decline, with Nintendo doubling down on the Wii U and not signing any games to fill the void.