ASML has market share, but they are also spending quite a bit on EUV tool development. Since it is in the best interest of the semi industry to have at least two lithography vendors, in the past Intel has made sure ASML and Nikon both got enough orders to stay healthy. Since the leading edge production tools are 193 nm immersion, that can still take place as Nikon is still competitive there.
ASML has definately taken advantage of the immersion market and the delay of the next generation tools is helping feed that lead as foundries buy more immersion tools to implement double patterning. Their future dominance will depend on which technology finally wins out and who brings the best solution first. It's all still very unclear suggesting that continued proliferation of immersion for double, triple and even quaduple (DP with double dipole) patterning will continue in the near future.