Under 500$ I think, or maybe depends on what the investors will do after the fork. But most forking resulted to a slight down but recovered and will rapidly increase. In short this Segwit2x will no difference to the last two, bitcoin cash and bitcoin gold but as Coinbase say good thing about this fork might be the difference but is this can affect bitcoin community’s decision. I doubt it will, for we do have our own mind to decide for what we think is right for our own investments, this is why I love cryptocurrency.