There's very little doubt that the moment cryptos-- as an overall concept-- start to represent a material threat the the status quo... the governments and regulators will start poking their noses into things.
Nothing will be "illegal" or outlawed... it'll just be made cumbersome and impractical... far more difficult to use than fiats and conventional securities.
Maybe it will be a bit like pot in certain places... you're totally allowed to OWN it, and even personally CONSUME it... but the instant you try to trade it you'll be hit with a wall of legislation and requirements and fees.
Exactly, with the taxes being risky, and now the SEC creating new risks in securities regulations, it seems that the community is going to be reduced only to people who can afford to hire a legal team to navigate the regulatory risks. That will basically raise a huge barrier to entry which didn't exist. Reduces the opportunity for the average person of course but maybe they don't care about the average person having the opportunity to make money as much as they care about the average person having the opportunity to lose money.