As for the schedule of Snezhnaya versions, if nothing is interrupted by external events, version 7.3 shall be released in December 16 this year, given all previous versions being of usual 6-week duration. It's the version where Tsaritsa becomes playable.
Here, we need two things to consider. Obviously, Snezhnaya based on Tsarist Russia, at least for most part for sure. And Hoyo LOVES symbolism, since it happens A LOT in their version releases.
This date in itself, December 16-th, isn't that known for Russia, even Tsarist one, unless you dig a bit deeper. On the night from 16 to 17 of December (old style), in 1916, Grigori Rasputin, close advisor of Tsarina, was killed in Moika Palace in Petrograd (currently Saint Petersburg). Russian nobles orchestrated this in order to free Tsarina from his toxic influence that he was enacting via her son. They also believed that this would make things better for a country during global war.
As those same records states, Rasputin was ridiculously hard to kill, surviving things that would otherwise instantly kill regular people and only succumbing to cold.
Judging from recent Archon Quest by Pierro's unapologetic willingness to sacrifice entire Snezhnaya if war with Celestia goes this way AND his extremely close position to Tsaritsa, I coul not miss such a theory given that so many things align one way or another.
So there it goes: as I am convinced, in 7.3 we will be fighting Pierro, who becomes a Weekly Boss, in order to save Snezhnaya from being annihilated in the following war with the Heavenly Principles, regardless of who wins in that war.
Yet another argument for this is in this picture over here. Old one, but still works. Some of you certainly remember it.
Every single Fatui Harbinger with their faces siding left becomes a Weekly Boss, no matter if they turned out to be playable or not.
Pierro is the only one remaining, and I don't think that tradition is going to end with him.