They close on phases.
See below, they'd have to reach Stage 4 for an onsite guest to be shut out. There is no way to guess what level it will reach but 4's are VERY rare and quite unlikely. And an ADR wouldn't help. I suspect the only thing it may see is Phase 1 and that is between Christmas and New Years.
Phase 1 Closure
Casual visitors are turned away at the automobile toll plazas. This means that people without tickets, those with one-day, single-park tickets, and those intending to use cast member passes will not be allowed to park.
Other guests may enter such as:
- Those with multi-day or multi-park tickets
- Those staying at a Disney Resort
- Annual Passholders
- Those re-entering the park that day.
- Those "hopping" from another park.
- Those with in-park reservations or appointments.
- Those arriving via Disney transportation
The following are dates within the past 5 years when Walt Disney World parks have reached, yet not gone past, a Phase 1 capacity closure:
- Magic Kingdom: December 25, 26, and 29, 2014
Phase 2 Closure
The only guests allowed through the turnstiles and into the parking lots are:
- Those staying at a Disney Resort
- Annual Passholders
- Those re-entering the park that day.
- Those "hopping" from another park.
- Those with in-park reservations or appointments.
- Those arriving via Disney transportation
The following are dates within the past 5 years when Walt Disney World parks have reached, yet not gone past, a Phase 2 capacity closure:
- Magic Kingdom: April 8 and 9, 2009; December 28 and 30, 2009; December 29, 2010; December 25 and 28, 2011; December 24, 25, and 30, 2012; December 25 and 30, 2013; July 4, 2014; December 31, 2014.
- Hollywood Studios: December 29, 2009 and December 28, 2011
- Animal Kingdom: December 28, 2009 and December 28, 2011
Phase 3 Closure
The only guests allowed through the turnstiles and into the parking lots are:
- Those staying at a Disney Resort
- Annual Passholders
- Those with in-park reservations or appointments.
The following are dates within the past 5 years when Walt Disney World parks have reached, yet not gone past, a Phase 3 capacity closure:
- Magic Kingdom: April 7, 2009; December 29 and 31, 2009; March 30, 2010; December 25 and 31, 2010; December 31, 2011; December 27, 28, and 31, 2012; January 2, 2013; March 25-28, 2013; July 4, 2013; December 31, 2013.
Phase 4 Closure
The park and parking lot are closed to all arriving guests. The only Phase 4 Closure in the past 5 years has been Magic Kingdom on April 7, 2009.