This could legalize bitcoin but it would also bring more regulations relating to it and would be taxable and counted upon income and other taxes.
In my opinion, bitcoin use was never a threat in an open society like US but it's categorization as money would provide more power to the authorities to control it. Though the consequences would be clearer with the passing time.
If you are earning an income, you should act like a citizen and pay the taxes. Bitcoin was developed keeping decentralization in mind i.e. to eliminate the interference of any third-party institution and not as something to hide your black money with. It is only fair if government imposes taxes on it and stops money laundering and other illegal activities.
Bitcoin or any other cryptocurrencies if left unregulated, will give rise to many illegal activities and also increase its usage as payment method on the dark web.