The event will be streamed and is free to view. Squenix has some important announcement so they are setting up an event to show their fans. Details can be found here.

If I had to guess, I bet we'll see a release date for Kingdom Hearts 3, and I bet we'll get a new trailer for FFVIIR. The rest will likely be mobile stuff or them showing off expansions for FFXV, Dissidia NT, and FFXIV.