rogelio, i agree. i said something similar when this issue came up sometime last year. if they straight up said, the "world X" is closing at the end of the season, people would rightfully riot, especially new users who were just getting started on their way to a goal. but if everyone knew in advance that in, say, 10 seasons worlds would retire and restart, or, if in the future they straight up said 'after 100 seasons all worlds roll over and everyone goes back to D3,' that would be a fair and effective way to do it.
the big plus to something like that is that you effectively get a "new world" without contracting existing worlds and without further dispersing a limited pool of coaches.