That's only if SegWit has been activated, and no large miners distance themselves from Bitcoin (here I am mainly referring to Bitmain with their contingency plan). If the latter becomes reality, it might initiate a short lasting bear market, but eventually we'll be walking out and move on. I must hower note that I don't think Bitmain will actually do so. To me it sounds more like an empty threat. Jihan once threatened to fork if BU reaches 50% support, but no actions followed....