@named coward, there IS no other method. Immersion litho is the workable way we currently have to process wafers below the 30 nanometer node (which is already old tech in litho terms).
The real reason Nikon isn't too keen on letting ASML continue in the market is probably because it's getting squeezed out of the litho market by ASML. Which is most likely because ASML delivers a better product (though I might be biased) for a comparable price. If they can put enough margin on the ASML price due to patent royalties they might get a better market margin.