I suppose the only system that will work in the long term without the need for resets (though why you would discount resets I don't know, as almost every leaderboard system in sport and the like relies on it to keep things interesting.) is something where the amount of points are finite, with no new points (other than new people entering the leaderboards) being introduced, and where the winner gains the losers points in some fashion, somehow linked to how many points they had in the first place.

Someone who's better at math will have to work it out.