The date probably won't be announced until closer to the run. There are two schools of though for Disneys race announcements.
The first is the Marathon weekend example in which they announce the following years date very close to the current years race and then open the registration just after the race is over.
The second is the RFTT and ToT examples where the date is announced 6 or 8 months before the run and registration opened pretty close to the date announcement.
I would assume the more successful the event the earlier the next years race will be decided on and announced.