No, at least not a permanent one.

The first problem that came to mind was in regards to linkshells, specifically small ones. There are linkshells that prefer to be self sufficient and with the current system it is entirely possible. If they have a deficiency in any crafting class they can fill it either with new members or existing members taking the craft up themselves. If we were permanently limited to one mastery then if a linkshell has a deficiency in that mastery they have lost a good deal of functionality and are very limited in the ways they can fill in the gap. They must either find someone who has that mastery, someone who doesn't have a mastery and force them to take that one or have an existing member entirely re-roll a new character just to get that mastery. None of those options are very good ones. However if they allowed us to switch Mastery for whatever cost/inconvenience this would be less of a problem.