Last year they announced it during nationals but this year nothing...
Kind of hard to announce it during any National Championship this year, since there aren't any.
Yes, the North American Regional Championship replaced the United States National Championship
but they aren't the same and not treating it as Nats by another name might even be why they held off.
Anyone have any idea on when it will be announced?
Based on their history, when even "emergency" rotations had a month or two of lead time... soon enough. Which probably sounds like another tongue-in-cheek comment, but I actually mean it; I don't recall
any rotation in Pokémon coming out of nowhere. Well,
maybe when Nintendo took over from Wizard's of the Coast, but even then we might have gotten a decent bit of notice. Maybe another old hand or just someone willing to do a lot of Googling can tell us?
I wish they followed a set time like MTG where rotation happens with the release of a certain number of sets that would be legal in standard (MTG at most has 8 at a time with the 9th set causing 4 sets to fall off on its release)
WotC would violate that rule if they felt they needed to; it isn't a contractual obligation so you don't really know, you just expect it based on their word and past rotations. FYI, while they controlled Pokémon, the WotC staff that regularly interacted with us told us things like how they had to get rid of the 15+ age bracket for competitive Organized Play. When asked about it under WotC's tenure, Japanese higher-ups with TPC were puzzled as they considered Pokémon a family game (not just a children's card game). That could have just been them blowing smoke, or at least being ignorant off the truth
but guess what? As soon as WotC lost the Pokémon license and Nintendo took over, the 15+ age group was brought back and has been back ever since. I am not saying that you should trust Nintendo/TPCi more than WotC, I'm saying not to trust either completely.
You can view a simple spreadsheet I made with the data
here; call the two earliest rotation dates outliers, and we've only got a week-long window for rotation; between August 28th and September 3rd. TPCi adjusts to the current situation, so a rule like that for Pokémon is made to be broken... or revised repeatedly just like the actual guidelines for when new cards are tournament legal. Odds low that we won't have an announcement a good month or two prior to the release, so you should have enough time to prepare. If you're trying to speculation on card values, welcome to why that is a job for pro's who can handle the stress.