The PR is merged now, so it’s deprecated:
But yes as Moin says you will only get browser console deprecation warnings for now 
When we first introduce a deprecation we are forced to fix all the instances in core + official plugins and themes, then for a while we leave the deprecation on and are able to gradually fix or let others fix third party themes, including customer themes.
This won’t become a permanent removal of user.groups for quite some time until we are sure we’ve caught all the call sites, and even then we start showing an admin warning first to sites that still have code calling the old site.