Yeah just learnt about that while switching between MSFS and MSFS 2024 in the drop down menu of Orbx.
I'm using Addons Linker and I'm not ready to give up on MSFS yet, so it's not too annoying for me. But I definitely don't like their approach, they shouldn't prevent customers to use products they paid for, as they wish. A "not MSFS 2024 compatible" scenery is still better than any default MSFS airport, I used EHAM from Flytampa in 2024 and the airport is running fine, there may be some imperfections but it still better than anything else (default or Asobo handcrafted).
No such issue with Contrail or the Inimanager.
So yeah in the meantime keep MSFS installed (don't install anything from the content manager if you don't use MSFS anymore) to be able to update your "non 2024" sceneries, and keep them installed in the folder you use for Addons linker.