+1. On the same topic, there is no notification for tags intersection either.
You can search for the combination by using the intersection search[1]:
http://forum.ansible.com/tags/intersection/TAG1/TAG2/TAG3
For example for awx + collection :
http://forum.ansible.com/tags/intersection/collections/awx
But there is no subscribe button. So keeping an eye for a combination of them also requires to check a browser bookmark right now.
[1] I originally posted about intersections here.