let me try to explain it with an example if I understand your request correctly. module version core-hybrid: aggregator-7.x-1.x = drupal 7.x contrib: aggregator-7.x-2.x and above core-hybrid: aggregator-8.x-1.x = drupal 8.x contrib: aggregator-8.x-2.x and above Yes, sounds good, one small step in the right direction, I support this idea.. I think it is a similar model how Acquia choose module versions, just much more strict.. one thing which I do not understand is what happens with the modules, which have files in the "includes" directory, like the menu module with menu.inc. I guess it won't be possible to change (improve) the menu.inc file in menu-7.x-2.x, but of course there would be a larger pressure on core committers if something really have to be changed in those include files for the new module versions..