The financing of any RWY extension is now dependent on DAA funds.
And the capacity of the DAA to raise funds is reduced by it being left with SNN debts.
But, as you say, the regulator has set a requirement that traffic at Dublin reaches a certain level (23 million passengers, I think?) before it would approve any increase in charges to fund the development.
Pity that the same logic wasn't applied to SNN.
Sadly for now the traffic levels in Ireland and the state of the country's finances will mean that any state support for such an extension is moot.
Well, there never would have been any question of State support for investment in Dublin Airport. That would be prohibited by EU State Aid rules. EU guidelines would not normal envisage support for any airport with more than 5 million passengers a year, and would only really envisage State support for airports serving less than 1 million passengers in areas with some element of disadvantage.