Even during the past splitting majority of the users were speculating that the price will lower, but the reality took place in the opposite manner with the price drop taking place to smaller extent and then suddenly the pumping took place taking it as high as $4900+, maybe the same situation happens with the upcoming November splitting.
Your comparison is not really helpful, because this time the majority of miners actually support the hard fork (or at least
signal that they support it). In the case of Bitcoin Cash that was not at all the case and the big mining pools only mined it
after gaming the emergency difficult adjustment.
In my opinion the big exchanges will be the deciding factor in terms of which chain will become the main BTC blockchain.
This is caused by their control over the desired BTC ticker symbol.