I suppose the biggest risk to anyone, especially individuals, holding BTC, are the Governments.
While they can't easily shut down the blockchain, Governments could shut down exchanges. Likewise miners, although they would have to act together.
Yes. This is what the governments can do. If you're in a country that have ease to exchange bitcoin to cash, they can ask the exchange necessary details about their users such as data and other information that could lead to taxation or stronger regulation and the worse, are those what you've said.
Two mitigating factors:
1. Big companies are major contributors to political parties, so big money talks.
2. Countries like Iran, Russia, North Korea and others, will step into the mining arena.
For us smaller fry, given that BTC supports decentralised protocols, might we see decentralised exchanges? Or exchanges operating in laxer jurisdictions, like The Caribbean, African countries, or nations unfriendly to US/Europe/UK?
Most likely, Governments will try and milk taxes from us all! Beware of Mr Sunak
About the decentralized exchanges, they're starting to gain momentum but they still lack of security because of the reports that some of them have been into hacking incidents.