All I can tell you, is after attending multiple New Years Eve celebrations in Epcot, we’ve never had any issues with disorganizion before midnight. I’ve never seen so many CM’s working in my life to make pathways/dance parties, etc…. as smooth flowing as they do.
The bottlenecks we’ve been in are right after the fireworks when the bulk of people are trying to quickly head out of World Showcase to beat the crowds. Which is much too late for that.

Lol.
At the same time, some people are trying to head back into World Showcase. There are spots that come to an absolute standstill. You just have to pack your patience.
We’re usually somewhere between Mexico and Canada at midnight, and we try to let the crowds thin out a bit before heading back into World Showcase. By the time we leave after 1am, it’s relatively peaceful and easier to catch a bus without too much of a wait.