The older and cheaper models of the ASML EUV sources would be good enough for this system that needs a much smaller power for the EUV sources.
The European partners of ASML are the only companies that could manufacture at this time the optical system.
Nevertheless, it is likely that the patent owners would prefer to license it to Nikon, to create competition for ASML.
Nikon should be able to make the optical system, but this could need a few years of development, unless Nikon already has a secret internal research project for making EUV mirrors.
The most difficult problem remains the EUV source, even if a much simpler source than the current sources is good enough.
It seems very unlikely that ASML would be willing to sell EUV sources separately to Nikon, providing components for competing systems.
The only deal that seems possible would be if ASML accepted to sell some of their older models of EUV sources to Nikon, in exchange for receiving licenses for this new improved kind of EUV optical system, which will then be incorporated in all new EUV systems, regardless if they are made by ASML or Nikon.
This would reduce the dependence on ASML and its partners, but ASML would still completely control the market of EUV sources, even if not also the market of complete lithography systems, like it does now.
Nikon's out of the EUVL game and doesn't plan on returning. They're reiterated this in just about every quarterly prospectus for years now.
They're migrating to licensing whatever EUVL IP they had to other players.
They've pivoted heavily to FPD Lithography (LCD, OLED, and potentially PV fabrication) - better margins, less political headache.