Jack, that's an excellent point with regards to teams that didn't win their conference receiving mandatory promotions to the WL. Definitely don't want.
What I would suggest is something along the lines of:
1. Mandatory promotions up to Pro league regardless of where you finished -- OR -- a roster reset and placement into a capped league of the owners choice. Basically, how it is now.
2. For WL promotions, same deal as #1 for the conference champs. However, if a team declines (and they will go into a capped league with a reset roster as a result) after that it is an OPT IN system in which teams are selected in the following manner.
** Did the conference runner-up opt-in
** other conference runner-up opt-in
** randomly select from all other leagues any conference runner-up that market the opt-in.
** any conference semi-final loses opt-in. randomly select.
** repeat with other conference semi-final losers that opt-in. randomly select.
** repeat with other leagues conference semi-final losers. randomly select.
...that gives us 48 teams to select from, should be enough teams with balls that want to promote. If it's still an issue, I suppose demoting teams can be given the option to opt-out of demotion