Universal just updated their Annual Pass Blackout calendar page. Most AP calendars only go through December, however the very last calendar goes through March 2016:
Ive included the March and April 2015 for you to compare.
Keep in mind the bulk of the 2016 blackout days start the very next day after the $79 CostCo Season Passes expire.
I think we may have a possible opening or soft opening date for Potter!