Dec. 28 and Epcot: Will it fill to capacity? Late dinner ADR.

[WDWDecember]

I'm wondering because we currently have a 7:30 ADR at CR for that date. Our plan is to go to Epcot in the a.m., leave to go back to our resort, and then head back later in the afternoon for dinner and the Illuminations show. I've seen on a few threads that since this time of year is the busiest, it's possible the park will fill to capacity. WDYT? TIA!