So, you can't use your BCH without worry? Why not just withdraw as much as you can into USD?
https://www.reddit.com/r/btc/comments/9sclqj/starting_to_think_about_ways_to_separate_coins_in/e8nsec3/
I could guess, when it's obvious that the BCH dust has settled and it's safe to. I'm pretty sure people will be quite vocal about that. Especially on memo. Great question.