I don't really care either way what happens to the old hubs themselves. However, I was planning to have jarvis go through pages and remove all the _a, _b, _c tags. First, because it's untidy to have tags around that we don't use anymore. And second, because people keep adding them even though they're no longer needed. I made an announcement post about it a little while ago, but apparently no one had read it.
So, if and when I do this, the old hubs will stop working.
On the topic of how reliable the new hubs are, I've been around the site for five years now without doing much unannounced disappearing. The update script is also on github: https://github.com/anqxyr/pyscp/blob/master/bin/update_pages.py . It requires very little setup - just pyscp installed and that's all. I fully believe that if I ever do disappear, any of our more tech-minded staff members can get it up and running in no time flat.