If it integrates with eIDAS, it doesn't necessarily have to be phased out. A very good pragmatic decision of eIDAS was recognizing that many member countries have different existing eID schemes, and federating them is easier than rolling out a new one from scratch.
it doesn't, but there is already a competing system based on the national id card, which is just simpler to explain to people ("you log in with your ID card" vs "you log in with a third party identity provider where you need to create an account"), and the people who championed the old system are no longer around.
