I think if stocks tank it might strengthen the foothold of the crypto-world. Look at precious metals. There's been a spike of interest in them. I am hoping btc and co gets that love soon.
There is no direct link between stock markets, metals and cryptos. Yes, if the stock market falls down then metals may go up because investors move their funds to more safer places like gold and silver but that doesn't mean that those traders move their funds to bitcoins. Because bitcoins are still not gained so much popularity in general and many people worried that if governments start regulating them then its prices may still go down.