I've also observed a much higher number of players in the channel from a /wc result lately. Sadly it's not from more people playing on Test though. So yeah, we are gradually seeing our community channel being taken over.
So ok, perhaps we make a test.testers channel then. The name should be a fairly big hint that it has an intended population.
We don't have to password protect it straight off the bat. That should be truly the last resort measure, but at least we'd have the option? But we circulate knowledge of the new channel's existence in a semi-private manner, using tells and guild MOTDs on Test.
No reason those who can still tolerate it, can't sit in both channels. Answer a few questions still, and keep an eye out for anyone who needs to be invited over.