Yes, it may be happening as we speak and over the next couple days. Bitcoin Cash could be Bitcoin very soon.
Nope, BCH price may have spiked and on other hand BTC's price dropped but it doesn't mean that BCH is on its way to kill BTC. BCH is still very young and no one knows how it turn out to be, all the more segwit is also incoming that could change few things I hope.
this is mainly market manipulation combined with great timing.
we all know that bitcoin price went up too fast, and we all were expecting a correction. like always the FUDsters use the short term movement only and the drop part. and then use it to pump something else at the same time. this time it was bitcoin cash. last time it was Dash an Ethereum and Ripple which were supposed to replace bitcoin by now!!!
as soon as people start looking at it as an opportunity to make profit, they will win. other wise they will sell at a panic (in a lower price) and they miss out when price recovers.