The success of Leinster is even more remarkable when you consider just how much of their intake is from a relatively small number of schools, particularly Blackrock and St Michael's. And it's not just Leinster it benefits, the likes of Carbery, Loughman, Conway, Jordi Murphy, Madigan all came from Blackrock. By my estimate, 7 of the team today come from Blackrock, St Michael's or Clongowes.
I'd say that if you're in the Blackrock senior team, you've probably got a 10%+ chance of getting a professional contract.
That is a remarkable success rate, especially when you consider that they're composing the team currently sitting at no. 1 in the world rankings.
Ardscoil Ris, Bandon Grammar, Pres are all contributing well into the professional game, think building on that, learning the lessons from Leinster, should be a focus over the long term.
Clearly having such a narrow source of players isn't actually damaging Leinster right now.