How would it change the UX (or UI) at all? Question and comment "scores" constantly change as they get upvoted (and occasionally downvoted). This would just be another factor in determining the present score.
As far as "theory" questions, such a designation could simply be another moderator privilege -- high-rep individuals would have the ability to vote to prevent a question from decaying. Perhaps an additional requirement would be that the question must have been transferred to Community Wiki.
As far as "theory" questions, such a designation could simply be another moderator privilege -- high-rep individuals would have the ability to vote to prevent a question from decaying. Perhaps an additional requirement would be that the question must have been transferred to Community Wiki.