It is very rare in Thailand that English teacher speak English in the class. I used to be a participant of English speaking training which was provided for English teacher teaching in the private school in my local state, and what I find out is most of the English teachers could not speak English properly and most of them couldn't understand when the trainer asked or instructed them something. In my opinion, I think Thai students won't be able to speak English except that they themselves want to learn it and practice it by themselves.