ECNL kicked Surf previously, so there are no sacred cows. Surf felt that boys DA was more important than girls ECNL when given an ultimation of all in ECNL. ECNL also let them back in straight away when DA folded, but I expect Surf very much want MLS Next, but they made their bed. Blues (all girls so no conflict) kept ECNL & GDA as they had the national ECNL title, but a decision point was coming (unless Blues won another ECNL national title) as I understand it.
In AZ, neither Phoenix Rising or RSL-AZ will give up the MLS Next, so if it is put to them, then I can see them both going GA. Alternatively, they might suddenly spin off a girls club only and a boys club only ... and then it would get really silly.
If ECNL need to threaten clubs to get their boys sides into ECNL, then their league mustn't be all that, and they must know it.