Those guys could probably get a run in existing first grade programs if they really wanted to. Nothing stopping the guys in 2s at Brothers from going to play at Norths now for example. The standards drop off between 1st-3rd grade at some clubs is stark compared to others - tells me that guys aren't necessarily "stuck" but rather wanting to play for a particular club.
Playing at a particular club is all about the culture or "vibe" of a place and I can understand why some stay.
On some basic numbers each year in Brisbane (SEQ)
9 GPS schools, 9 AIC and many others
Say 20 schools with 1st 15 Programs x 20 players = 400 people of higher skill / standard
Double or triple it for 2nd XV and 3rd XV = circa 1000 lads capable of playing the game
Some go off to other state/countries or Bush so expect say 700 bodies available to go into colts programs (plus those that arrive from outside the local school programs)
Currently QPR has 9 clubs with average 3 Colts teams = 675 spots to fill
As this is a 2 year age group ie U 20 there is in effect only 330 spots for 700 people to fit into.
And I haven't included those stalwarts of every school / club Fighting 4ths, Filthy 5ths and Sexy 6ths
No wonder plenty say F&^K it and don't even keep engaged with the game.