An update: We will be moving up to OOTP 15 after our next season.
That means we will play one more season under 13, which will begin on or around March 8th, and after that season is completed we will then move the league into OOTP 15.
So, if someone is looking to join a league but doesn't want to get "stuck" in a 13 league, here's a league to join.