It's very difficult when you hear of a feature that is just simply something you don't want in your game.
I can only suggest waiting until we know more as it may be that you can simply not schedule the holidays with the new calendar which would solve your problem I think. Honestly one of the largest issues with TS4 is it's lack of toggles, or some other feature, that would allow players to customize their game as they wish. But, maybe... maybe the calendar does this to some extent.
It might also be that these holiday events can be cancelled as soon as they start, much like surprise pop-ins with the apartments or indeed the base game parties, which might also be a possible work around.