Not necessarily. BTC is the main crypto in large part to it getting all the press. If the current press continues, there is a slight chance BCH could surpass BTC. I'm not convinced I'd bet on it, but those invested in BCH now are going to become extremely rich if it happens. Of course, another new crypto could come along in the next few months or years, and that might actually become the main crypto. Then it won't matter.
If enough major investors switch over the BCH, or more services start using it, and it starts getting used regularly, then it will surpass BTC. I doubt any exchanges will switch to calling BCH just Bitcoin any time soon though. BTC will likely have a slow death, if at all.