I don't see why we would need a new key at all. The game has status as "Early Access Game", and I guess anyone who have access to the "Early Access" version will simply be patched up to full version at launch. Isn't that how it usually works with Early Access?
The people needing a new key are only the kickstarter backers (if you bought it on steam then you don't need one), and that's because some people wanted to try out the beta but want their keys on GOG.
