Very different effect on men & womens.
With the girls, it is hard to see any more than two divisions anyway. There are 13 teams in the U21 comp at the moment, with no team from Eastern Mavs. To run a viable Div 3 would require another 13 teams (as 10 teams required in Div 1).
Thats about another 100 players, which would require retention of every second year coming out of U18s (say 70) plus another 30 older girls that aren't playing U21 at present. Not impossible, but difficult since what is offered is similar to the current U21 competition.
As for guys, I can't see how we have improved retention for a bottom age U23 player who has played Div 1 since U12s but is now being asked to play Youth League Div 3. The problem isn't elite v the rest, the problem is the players that were elite in the juniors that are no longer elite in Youth League.
The success of the Youth League will depend on what the ABL teams that train Monday nights decide to do with their training. If some clubs move those trainings to Tuesday nights, the Youth League will struggle as the players will prefer to train under the ABL coach rather than play YL.