I've taken a break from working on this, but I have a question to ask on behalf of the Namecoin devs.
Would Armory devs merge Namecoin specific transaction types into Armory if someone were to code it? This could be used in conjunction with an Armory plugin to automatically renew domain names to prevent expiration.
I don't think we have any plans to commit non Bitcoin code to our official repo. However, I can make key methods virtual (or create a fully virtual parent)s so someone implementing NMC or other coins can derive our transaction and block classes for their own purposes easily.