Nice! Yes, convertibility seems to hang on those three exchanges.
30 mins ago @exyle said Steem was also disabled on Bittrex:
https://steemit.com/life/@exyle/vlog-67-steemfat-diet-and-gym-bitcoin-cash-and-steem-withdrawals-and-deposits-disabled-on-poloniex-and-bittrex
There seem to be some battles going on at the top of the pyramid. Interesting times!