Final Fantasy should always try some new things, if that eventually takes them down some less traditional JRPG paths, so be it. Probably some group of people will like that version over the others. FF is like that, few people like all iterations of FF, even I do not like IX.
I think though that the sand box style should be left to the MMO side of things, where it can really shine. A turn based sand box style JRPG seems like an oxymoron to me.