Square Enix are fucking morons. They should have shifted the mainline Final Fantasy games to handhelds. There, they would have had no competition. They could have been able to continue doing traditional, turn based games. They could have avoided entering the western 3rd person action game graphics arms race. They could have avoided turning mainline FF into a freaking action game.
IMHO, after Final Fantasy 13, they should have made the switch. I bet, a proper mainline Final Fantasy 15 game on handhelds, could have sold 10 million copies in ONE year alone. They would have established a new, easier to please consumer base on a platform, where graphics don't matter that much (therefore you don't have to spend your entire budget on them), to producse something that stands out. They would have stood out not matter what. Spending an AA home console budget on a handheld market would have yielded them an AAA quality game (just in terms of visuals ans presentation).
If they actually did that, they would have been a good chance they could have developed Final Fantasy 16, 17 and maybe 18 by now, with all of them selling 10 million each easily.
HOWEVER... having said that, I just realized, this would have meant they would have needed to focus on stories, content and gameplay with these hypothetical handheld sequels. I'm not sure if they still had the talent to do that after FF 12... Anyway, it would have been worth trying (and maybe hiring the right people) instead of trying to suddently be an AAA western action game developer, which they ultimately miserably failed at.