If you mean landlines for Phones: The fiber can handle that, and does, but people are indeed dropping their telephone-number-for-a-house subscription in favor of individual cell phones (and my Phone is generally on WLAN-call when I'm at home, so it use the fiber as well). My parents in law were the last ones I knew with a house-based phone number and they dropped it this year. That said, I think you still get a house-telephone-number for free with many internet subscriptions and the ISP's modems have ports for Phones on them, so indeed the landlines as defined still exists, but it's a matter of definition.
Do you have a source for this? All I can find is this quote [0], which is a long way off from "all landlines":
> nearly 1 in 2 homes in the 25 largest cities will have KPN FTTH access by the end of 2021.
[0] https://glasvezelnieuws.blogspot.com/2021/04/kpn-op-schema-m...
As for ripping out the physical service entirely, I don't have any numbers but I saw the lists from 2020 and 2021 and they are huge. So it is clearly happening. And they have been doing this for quite a few years.