What does "roll out" mean here?
Popups are nice and all, but can really get in the way of contributors, so there must be a way to disable them for good.
Beta Features provide a nice UI for introducing them to the general public, why not to have a similar 'less beta' section in preferences?
Quick reply here...
It is already possible to disable the feature, for both logged-in and logged-out users. It uses the same method as Reference Tooltips (cookies or localstorage). Click the cog-icon on the hovercard, to do so.
See docs at https://www.mediawiki.org/wiki/Beta_Features/Hovercards#Enable.2FDisable (needs updating, but basically covers it)
for a version of M17 that includes referencetooltip/hovercard/navpopup controls. I only removed it because someone said it overcomplicated the initial version/idea. (More details, and many links, in M17)