If a major hack occurs, then it will affect the reputation of Bitcoin and the exchange rates will go down. It is a vicious cycle. First, the exchange rates rise. After that, the hackers become active, attracted by the high rates. And finally, the exchange rate crashes, after major hacks. Back to ground zero.
It is just a minor set back. just like when bitfinex was hacked last year, the price went down a bit for some time but it bounced back. As long as the one hacked are the sites, then the price will bounce back. But if bitcoin or blockchain is hacked, then that is a different story. But I doubt there is a hacker right now that can hijack blockchain and compromise bitcoin.
