It looks like Marriott backed off upping the category of these New York Manhattan hotels. They were all listed as going from category 5 to 6, starting March 5th 2019, but they are now still at category 5:
There might be a bunch of other worldwide properties that didn't undergo the category hike

Sheraton New York Times Square also did not change to 6, it remains at category 5.

Aloft Harlem went down from Cat 5 to Cat 4 which makes it a great New York redemption using points.... especially when they're charging as much as $600 a night in some instances.

I mean, it's great that these properties didn't go up in price, but I don't love the implied precedent that category changes are not just limited to a single, well-publicized annual event ... does this mean properties can also jump up in category at any time without warning?

Yes. It has happened in the past and will likely happen again.

More likely someone just forgot to update them ;)

I do know at least the Residence Inn Central Park did go up right after the change as I booked an award stay there for December the day before the change. I checked a few days later and it was a Cat 6, so maybe Marriott decided to change some hotels back or maybe it is just an IT glitch now.

very unlikely as some (if not all) of these properties increased to cat 6 after march 5th....at some point between then & now they have reverted back to cat 5....so maybe marriott or the property changed their minds about the cat increase....

I've had two separate reservations that I booked prior to March 5, 2019 honored at the old rates (booked using points advance). Does anyone have experience with Marriott actually deducting the points they add to offset the award pricing change if you change/cancel your reservation? I have a 3 night award stay booked but really only need 2. I want to reduce it to 2 nights (ideally keeping the 60K/night award rate).

Let me know!

Following up as promised - my cert finally been posted. Switching the points for the cert was not a problem over the phone (I did need to ask for it specifically, as the agent told me that the new rates are higher than the certificate - but manged to do it without a problem). The key here of course that the night was already had a certificate attached to it using points under the old rate.

Just seeing this topic at the top of the Bonvoy forum made my stomach turn! I thought....here we go again with the next round. I really need to be more optimistic.

I noticed the Sheraton just went to category 6. All the other NYC properties that did not change (as listed) on March 5 are also category 6 now:
Sheraton New York Times Square
Residence Inn New York Manhattan/Times Square
Residence Inn New York Manhattan/Central Park
Courtyard New York Manhattan/Times Square
Courtyard New York Manhattan/Central Park
Courtyard New York Manhattan/SoHo

No more cc cert usage in Manhattan :td:

There are still plenty of properties in Manhattan where the 35K cert can be used -- at least in theory, if you can get around peak day restrictions. Courtyard Fifth Ave, Fairfield Fifth Ave, Springhill Fifth Av, Courtyard Herald Sq, Residence Inn Midtown East, AC Times Square, etc.

There are even a couple of hotels in the Financial District where the 25K certs from the old Chase card could still be used, again if you can manage to avoid peak dates (or where the 35K cert could be used even on peak dates).

Closing this thread as we are now into 2020. Once the 2020 category changes are announced someone will create a new thread for that discussion.