I'm not sure why bitcoin and some altcoins are still connected. Many exchange opened alternative sell option between ETH/Alts, or BCH/Alts. Yet BTC has still major influence.
I guess something is going on behind the doors. I especially looking forward for the tether audit results. If it fails, there maybe big crash first and then ETH & BCH might go moon rapidly.
Please check BTC graphs, it looks like controlled decrease, rather than sudden drop. Again...something fishy is going on.