This is cute and all, but it seems like a lot of new complexity for no really important purpose.
Not complex, really. 1) Add copy namespace 2) Change "protected page" link to "Edit copy" 3) Add notice about page replacement 4) Implement
Making more people sysops is not a good solution. Some people do not want to be sysops because of the responsibility, others do not know about the sysop/user distinction and just want to make a quick fix to a protected page. With an increased number of sysops, the likelihood of abuse (the most obvious being banning and protecting pages unnecessarily, both of which has happened) obviously increases. Also, you get more and more of a power hierarchy, which is very un-wiki.
The protected page change would have no disadvantages I can see.
Regards,
Erik