User blog comment:TimmyQuivy/On the Importance of Upgrading MediaWiki/@comment-1998339-20200507171442/@comment-1998339-20200507172743

That post explains the fate of Oasis, but doesn't answer my other questions, particularly the one about selectors. Changing element selectors like those mentioned will seriously break a lot of custom code that relies on such selectors to apply styles to specific elements. Ideally, I'd like to know in advance if the intention is to change  to   or something along those lines.

Also, that blog post says nothing specific about custom user groups. Will those be available to communities by request?