So at this point I honestly don't know who to believe BUT I have a question for the OP (and please the OP only).

Will BTC in Bittrex or Coinbase be credited with the new forked coin or not?

I also saw a twitter post saying Binance would be supporting it: https://twitter.com/search?q=segwit2x+fork&ref_src=twsrc%5Egoogle%7Ctwcamp%5Eserp%7Ctwgr%5Esearch

So what's the answer to those questions