Our plan from the beginning was to make the best Final Fantasy game available. That is our vision for XIV. Then we thought, how can we make the best FF game and we came to the conclusion that it would be an MMORPG. It was decided to make the best FF first, then led to the decision to make it an MMORG and use that genre.
MMOs are normally much larger scale than any regular game. It isn't something that you decide might make the game better - such as Resident Evil did when they decided to make RE5 online.
MMOs are designed to be very time consuming. To keep players playing for many months up to several years. Your normal Final Fantasy game is meant to be enjoyed in a relative short amount of time. If this game was truely designed to be a normal Final Fantasy game, and the designers thought it would be better online, it could still technically be a Masively Multiplayer Online Role Playing Game, but without time sinks and without intentions of being the game players will play for months or years.
There have also been strong rumors that the game could very well be free-to-play. This was asked in the interview, but it was neither confirmed nor denied. Obviously, if this is a true MMO made by a powerhouse like SquareEnix, it is very unlikely to be free-to-play. But, if it is like their spokesman said, a Final Fantasy game first and a MMO second, it could be small enough that a monthly fee would not be fesiable, and the game could actually be "completed" (in some sense of the word) in a much shorter amount of time than what the community has come to expect from an MMO.
It's all speculation right now, of course, but I might advise cutting off all ties to FFXI until we find out more.