Losing the seigniorage income might well be a worthwhile concession in return for a free trade agreement with the US. Clearly, there are lots of potential options. There can be little doubt that this issue will be a matter for public discussion and debate for a considerable time to come.
I believe the Reserve Bank has already made a constructive contribution to that discussion, through the publication of a number of papers relevant to the issue. But it is crystal clear that currency union is not a magic path to substantially faster New Zealand growth. It is no substitute for domestic policies that promote stronger productivity growth.