"All right. Shall you be here tomorrow? We're coming."
I believe I understand the traditional (but complex) rules pertaining to the use of "shall" with 'you' and 'I', but why is it "shall you" here?
Although it is rather strange, the use of shall in your sentence is likely to be interpreted as a command [ we ask you to..] or as a promise previously made [I don`t know the exact context] by the second person you in your sentence. I am not sure but, anyway, it sounds pretentious and not familiar to me. When I say pretentious , I refer to the fact that I have encountered such unusual uses of shall only in the Bible.