Years ago when I was still active in youth soccer club politics, I proposed that the big 4 North County Inland clubs (Poway, RB, PQ, and Pegasus) could combine in a way that would result in a virtual super-club without giving up their individual characters. Each club would supply their best players to a team nominally managed by one of them, with each club managing a different birth-year team. For example - Poway gets BU15, PQ BU14, RB BU13, Pegasus BU12, and the team holds together from year to year. East county teams could have done something similar.
What has happened instead is that three of those clubs have merged into SDSC, with Poway hanging on independently.