Registered users must know how much time a page (any namespace) will remain in their watchlists. To this date, to find out how much time left, either I must go to Special:EditWatchlist, or I must go to a page that I'm watching and then hover around a "half-star" icon to see the "alt" message.
There should be some kind of a pop-up notice telling registered users how long a page will remain in their watchlists within short time (maybe 24 hours or less, or two days?) before a page becomes de-listed. There should be also a pop-up notice telling them that a page has become de-listed when (or some time after) the expiration arrives. Either pop-up notice should also ask registered users to either extend expiry time, de-watch the page, or (implicitly?) let the time remain without taking any action.
If a pop-up notification isn't desirable, then there must be another some sort of feature doing what I'm requesting above.