Im fine with leaving Taiwan out. It wont jumpstart a new forum as much without though, but still there is significant traffic on mainland carriers to justify a forum, and the upside is huge, with all those carriers, FFPs and members of main alliances.
Actually splitting mainland and Taiwanese carriers can be benefitial to the other forum,and with a sticky on Taiwanese there, as well as total number of posts on these are fewer, it might be better to let Taiwan stay.
It can possibly help reduce confusion on China airlines vs Air China as well.