@eeks Slept on it and have realised I probably did get it backwards - ETC is the one that will have to fork because of the way ETC is being credited to ETH holders on exchanges (not the other way round). Sods law - I can't correct it now!
Anyway if magically the ETC people reverse their stance and do HF we could end up with 3 different chains as some people will inevitably resist that HF too. The possibilities just get more and more crazy.

This stuff is making my head explode now!