Got a bit more info on the NPL -> N1L transition from my son's club. I don't think this was posted here yet (and apologies if it was and I missed), but might be interesting to some.
To "stay" in N1L, a team must have a reasonable record (unspecified, but aligns with the "not bottom three" mentioned before), but must also have 8 or more players returning from the former NPL team. This disqualified over half of our club's former NPL teams, particularly with the age changes this year.
Maybe more interesting was the club's perspective on the whole N1L integration change with ECNL, though, as stated:
There's no current promotion path into ECRL+ from N1L (just the "opportunity" for high N1L to maybe play some of those lower teams); ECNL is a walled garden of existing large member clubs, who will preserve this to poach the good players (as the only chance for them to move "up"). SoCal League is being encouraged to preserve this, by not allowing players registered in any external leagues to play in their league at all (basically, to try to coerce clubs to not seek alternative paths like EA/MLSN, as this creates an internal wall for their players). More materially, the club also views this structure as a "dead end path" for team/club progression: by playing in SoCal League, you're essentially designating and limiting your club as a "feeder club" for the clubs in ECNL (and if you get good enough, your good players will just be forced to leave). This is considered an unacceptable state for the club, which aspires to have high-level teams within the club.
As a result, the club will be looking to move away from SoCal League, focus on EA+ on the boys side (and DPL on the girls side), and seek alternative leagues for lower teams (eg: PSSLU). This won't happen completely immediately (momentum), but they seem convinced that future SoCal League participation will be detrimental to the club, given the "pathway" which ECNL clubs are pushing, and they intend to try to avoid it entirely in the future.
I'm unsure how much this applies to any other clubs, but it certainly feels like this is going to push the wedge further between the different competing pathways, given the club's perspective. I suppose this is an opportunity for expansion of competing leagues now.