Regardless of the choice, where is the storage of the selection to reside? In a client cookie? I object to storing any of this server side based on client ip address.
Topic on Talk:Beta Features/Hovercards/preferences
I would assume a cookie. I agree that server-side by IP would be inappropriate. ~~~~
It uses localStorage so it is tied to and private to your device. In future we could tie storage to account details for logged in users but we don't have any plans to just yet.
It is already possible for IPs to re-enable hovercards once they're disabled via the cog icon. We used the same system that Reference Tooltips does, as explained/illustrated at Beta_Features/Hovercards#Settings. However, this isn't perfect, especially because of localstorage issues with Firefox (see phab:T66721#2014128 and others). I'm not uptodate (nor a developer) on the technical details and issues though.