MdCN and Storm Shadow aren't interchangable either because the missile is different, AFAIK the only real difference between VL TLAM and sub launched TLAM is that sub launched has a sleeve to allow firing from a torpedo tube so there's more commonality with that than MdCN and Storm Shadow IMO because the airframe is longer for the former + also has something like 4 x the range so it's hardly equivalent.
I'm all for supporting indiginous missile capability, but if that comes at the cost of capability (MdCN has 1000+km range - TLAM has ~1700km) for a negligable financial benefit then i'm not so sure. Is there any reason why they'll open a production line in the UK? As France is currently the only buyer AFAIK then chances are the initial production lines are being run at MBDA locations in France so we may - ultimately - end up just buying them from French plants.
As to being "dominated by the French", MdCN is a French concept (hence the name) so it comes down to buying from the French or from the US.
Meteor is a prime example of Europe producing a world class munition with many interested parties in Europe (and probably abroad with export customers), personally I don't think we'll see that from Europe again until Perseus comes around which - according to Janes - has been developed in consultation with the RN and the MN (i.e the 2 biggest navies in Europe) so they're probably interested in adopting it at some point in the future post 2030.
DSEi 2011 - Perseus: MBDA’s missile of the future?
My prediction is that most maritime defence weapon systems MBDA puts out will be aimed specifically at the RN and MN - it's the economically sensible thing to do but has it's issues - but is now the right time considering the current variety in both countries missile stocks?