MiLB-X leagues are a user-driven customization on top of the Ottoneu platform. There are no plans to further support these customizations at this time. Only a small percentage of leagues have this customization, and it breaks two of the core tenets of Ottoneu- every player that is on a team must be paid and team rosters are maxed at 40 + 60 day IL players.
If you and your league enjoy this customization, please by all means continue to use it. However, at this time I do not plan to prioritize any effort towards making these customizations part of the Ottoneu platform, especially given the other features I would like to work on before the 2020 season.