That's a guess.
The "unknown factor" is that the parks have all been getting busier and busier each year for quite awhile.
What happened in the last few years may or may not apply to THIS year.
I'd estimate that you have better than a 50% chance of getting into MK if you have an AP, and/or are staying at a WDW resort during
that trip. But, again, that's a GUESS.
If you REALLY want to be inside MK during the busy holiday dates, arrive before 10AM and stay in the park until you're done there for the day.