@kiwidude
For the handling of newly integrated plugins as the updater you could invent a routine. What should this routine do?
- On first start after installation (or with every start depending if the second routine doesn't exists) check if a deprecated plugin has been installed.
- deinstall the deprecated plugin/s
- give message of deinstallation
- restart Calibre
The second routine is part of the updater, it checks if the deprecated function is to be installed and denies installation and gives error message.
I know, this is only possible if the plugins are installed under their official names, but I assume that nearly everyone will have them installed this way. The last remaining are just calculated losses.