http://kotaku.com/5467331/there-will-never-be-another-final-fantasy-game-like-ffxiii what this means is that it cost the company way too much money to make the game. so the next final fantasy game would be even higher and square doesn't want to do it. but being small and efficient is a hard thing to do.
Of course there's not going to be another dev cycle for another FF like FFXIII. Considering that they had to port it on the 360, switch art styles, and go from the PS2 prototype to the actual PS3 version. Where did it say that Square didn't want to do it? What does making it 'higher' even mean?