I'll reserve judgment to see exactly what this means. The game's plot is already fundamentally broken into discrete chunks, so I think it should be possible to release the story episodically without negatively impacting the overall game -- which is to say, that once all episodes are released it should be a "full remake," which is exactly what they're advertising.
I actually had a hunch that this might happen, when I saw how close to finished the prologue looked in this trailer. "They could probably release a prologue demo right now," I thought. And then I thought, "Huh. Prologue. I guess doing this episodically is one way they could make sure to get this out in time for the 20th anniversary."
Having played Final Fantasy Dimensions, I don't think that the episodic concept is necessarily a bad one. Even though it was originally released episodically, the full game just feels like a standard Final Fantasy game, where you progress through the scenario from town to dungeon, dungeon to town. Backtracking is allowed as new episodes are released, and the game opens up in the final episodes when you get the airship.
The potential positive of this, like I said earlier, is that this is a way they can get it into the hands of players before 2018 or 2019. I can't exactly object to that.
Again, assuming of course that they're effectively releasing the full game in chunks as they develop it and finish up each section of the narrative.