would there be enough players interested to fill even a single league with old players? That would be, minimum 30 teams * 40 players per team=1200 old players at least.
Doing a search for all players 481 days or older, level 1-100, of agents who have logged in within the last 3 days, shows just under 61 full pages of results (25 players per page) for just under 1525 total players.
If you went to a more realistic 603 days old or so (3 seasons in decline) would drop significantly as many of the current 480's players haven't even had their first decline yet and are still playing on regular teams.
There simply isn't enough playerbase to support this. Even if it was implemented (which it won't, they have stated many times they don't intend to add any more types of leagues) most people retire their players for flex to make new players. I suppose you could say the base would slowly grow over time as new people age but i don't see enough people being interested in joining something like this.
