My guess is that basic development covers the overall idea of the game. Basically what they want the battle mechanics to look like, open world vs. more linear design, what types of quests and bosses they want. They may likely even have some prototypes made up which is likely what we saw in the trailer.

Now they're going to build the game to meet those expectations. It may mean we still have a few years ahead of us before we see the game, but at least we know they're out of the planning stages and won't be having another "Versus XIII" situation where the game stayed in pre-production for five years.