It's planned to rededicate A540 to B59. It was announced to happen by January 1 but it didn't.
It might happen soon but it could also take some time. There will be an announcement in the
Amtsblatt (Government gazette) of
Bezirk Düsseldorf. And the official map is usually updated within a few days:
https://www.nwsib-online.nrw.de/