Whether or not your provider continues to support CableCARDs is entirely up to them, thanks to the FCC decision in 2020 that IP based apps on third party platforms provided users sufficient choice over renting CableCo hardware.
Even then, the limitations of CableCARD and the eventual dead end were obvious to Tivo, and they backed
AllVid. The FCC refused to vote on it and it was dead in the water as cable MSOs just developed their own IP based apps.
In turn, the cable companies have chosen to develop or license proprietary platforms, and they are not obliged to license or test them with Tivo, or grant Tivo access. And why would they encourage a third party competitor above box rentals they profit from?
Now generally you only see the cablecos begrudgingly offer their IP based apps on the third party hardware platforms that had critical mass long before Tivo released the stream (Roku, Apple TV).
This is not Tivo sitting on their asses and doing nothing, at least not at present.
The one fatal flaw I see is that if Tivo had been more bold and future facing, they could have been Roku before Roku. Yes, the Roamio series had streaming apps, but Tivo could have used their brand to launch streaming only devices while Roku was still nascent, with the Tivo brand recognition and lower hardware prices. Yes, I know the Roamio OTA came in at $49.99 base, but that still had a requirement of Tivo service at $14.99/mo or $150/yr. But the Tivo service is a sweet consistent income stream, and they probably worried about a combination of cheapening their brand and going lower margin on hardware + no ongoing service.
Tivo recognized the importance and growth of streaming - hence the Roamio having key streaming apps - but they failed to take the plunge that could have made their business irrelevant. Roku made the better bet on the market, and by the time Tivo realized that, it's too late. It's now a chicken/egg problem where Tivo's platform does not have the critical mass to make streaming services and cable companies feel that they
have to put their app on it or else.
In terms of CableCARD support, how "dead" it is will vary based on your operator, service region, and rollouts. Most fiber deployments in the US were not QAM. The newest NGPON2 from Verizon FiOS doesn't send TV over QAM either, but most people are not signing up for 2 gig+ service and still have older FTTH PON that support CableCard. Spectrum is posturing hard in a lot of their service territory, but is apparently willing to provide the high split converters required to keep CableCARDs working upon request. Comcast is not providing new CableCARDs as of October 24th (from what I understand there is a coin cell battery in these things, and you may want to swap out a cablecard while you still can if you have a really old one... bit of a dice roll vs. programming/pairing though).
A more accurate statement might be Tivo/CableCARD are dying. It will work up until your cable operator goes IPTV only and doesn't send channels QAM, or until your cable operator doesn't want to support cable cards. That could be a month from now, a year, five or more years. But it's an incorrect blanket statement to say that all CableCARDs are dead in October for all regions of all cable operators in the US.