At least that's how I'm reading this by Brett McMurphy. The Mountain West and Conference USA might not form a whole new conference after all, but could instead just have some sort of formal arrangement. If a 24-team league is no longer on the table, then you can go ahead and keep the table, MOUNT USA, as you've just upset fans of enormous institutions everywhere.
The main reason for dissolving was to nullify their current television deals and then creating a new conference to maximize their media rights revenue. However, if the leagues dissolved, then they would lose their NCAA tournament units -- teams earn about $250,000 for their conference for each round they advance in the NCAA tournament and that money is distributed to the conferences after a rolling six-year period. Dissolving the leagues would forfeit C-USA and the Mountain West millions of dollars.