That's what I'm expecting. It's going to be chaos.
Though interestingly it might be chaos that can be helped somewhat by people forming parties. Am I remembering right that everyone in a party has a chance to learn the enemy skill? Would encourage people to group up instead of playing solo next to each other.
Still, swarms of blue mages descending like locusts upon every last monster in sight.
This may be the worst choice they could make for delaying one piece of the patch content. If it came out last week the effect would be more staggered while people prioritised different things, but now it's the one new release that everyone will be trying to do at once.
Maybe they didn't want it to interfere with the Heavensturn FATE or something.