Plugin groups would be just like mix and edit groups. there could be 2 different types of plugin groups. control groups that link parameters so that when you change a parameter, it changes globally on all plugins in that group that are the same plugin. the other would be bypass groups which you could link any plugin to the group and bypass all the plugins in the group globally.
i have a lot of tracks that are doubled (or more) and use the same plugin on all tracks. it would be nice to be able to hear the parameter change to all the tracks at once without having to automate or copy them one at a time.
i also like to bypass all the plugins on certain tracks to compare the processed and unprocessed sounds. would be nice to not have to bypass them 1 slot at a time