Yes - we anticipated such a panic, and plan to require as few new projects as possible. In all cases, we're replacing harder projects with slightly easier ones (and all projects will be much easier now that they have test suites that will help eliminate ambiguity).
As for some people having more than 6 certificates, this will be a very small number of people in the grand scheme of things, and having the old certificates will distinguish them as early campers.
For example, now if you want to create a Twitter account, your handle must be at least 5 characters long. But there are still thousands of people with Twitter handles shorter than that.
I don't think new campers will think too much about this, but seasoned campers may notice and respect the fact that someone completed one of the old certificates "back in the day."