It makes sense. Notification will not take this long if it is just a minor update, and only takes few hours to let the customers know. Right now, there is none yet, not even on discord. So it must be the hash algorithm, since that is the one that takes the longest to decode. And requires a lot of effort.
There is no one to blame here though. Niantic updated, and there is nothing PF can do about it. The staff, they cannot post any update until hatchingegg let them know what is going on. And hatching, he is probably busting his a$$ right now trying to understand the new algorithm and how to break it, or probably on the phone right now with other devs, which is more important then reading the posts, that's the mods and other staff are there for.
And us customers? Well, the good thing about this down time is that it will give me time to bring all my accounts back home, most of them are in Japan, China, New York and Frisco. If this Nov 23 event is true, then it's just perfect. The safest way (and slowest) to use lucky egg and evolve is to do it manually anyway, but player can only do it manually when he is back home. Imagine a 2000xp per pokemon evolution. that's almost equivalent to 20 pokemon catch, minus the stardust. But this downtime might also give me some time to take over the local gyms and collect my daily pension. I can see violent war in the gyms nearby this next few days when all high level botters decided to come home from overseas, loaded with max revive and max potions, until we all ran out of it. This would be fun.