There is somewhere between a 99 and 101 percent chance that monero will be illegal someday. Plan accordingly. The good news is none of us have any monero. We all lost it in our boating accidents.
No need for them to do that, they will just control the entry and exit points to fiat, e.g. the exchanges. Making it illegal wouldn't be in their interest, it would make it even harder to control, and basically advertise for it. It could still be traded on decentralised exchanges.
It's much more likely that they will enforce people to declare all crypto tradings than to straight outlaw a crypto.