Stock market may be quite outdated, but they could easily migrate to blockchain technology if it becomes widely regulated. Once the blockchain gains full steam ahead in the real world, then you could expect businesses, companies, and even governments using it for their benefit. Migrating the stock market to a distributed ledger would not be that difficult to achieve, and it would provide cheaper costs, as well as, fast trades. Right now, cryptocurrencies are the choice because their technology is superior, and anyone can get in easily.

But, if the stock market makes the change from its outdated technology towards modern blockchain technology, then I'm afraid that legitimate investors would prefer to buy and hold stocks more than a cryptocurrency. Unless cryptocurrencies become widely regulated by governments around the world, I don't see any reason why serious investors would want to migrate from stocks to cryptocurrencies. Sure, cryptos bring huge rewards, but they're also extremely risky. There's no protection against hacks, you cannot make disputes about a transaction, there’s volatility or instability in price, which makes cryptos terrible for short-term holding.

All in all, I guess that it depends on the person's choice if he or she wants to invest in stocks or cryptocurrencies. Some people I know of, invest into both to diversify risks and gain their respective benefits. But, due to the freedom cryptocurrencies provide, I think that many people would choose them over stocks in my own opinion.