They can't block all the sites of cryptocurrencies and wallets because there are so many programmers out there that can and will find a solution to make and continue the cryptocurrencies.
It's called
Virtual Private Network (VPN). In China, famous social media sites are actually blocked. There's a documentary about this and all they do is use a VPN. The only downside is that VPN slows down the connection a lot. People don't want to miss out with what's going on and will always try to find out what the government is trying to hide to them. So when all crypto websites are blocked, people will be curious and try to find out '
what's behind the wall'.
They can't block sites to prevent reaching your wallet. but they can track your bank account to get tax.
What I see as a solution is people selling their bitcoins in exchange of Paypal funds. It's a digital currency and you don't have to put the money to your bank account. The money doesn't have to be seen by the government. This is a very easy solution to the "government banning bitcoins" problem. You get your Paypal verified. You do a P2P transaction with someone from a different country. And then you spend the money on Amazon, eBay or whatever online shopping site that you locally have. They are accepting Paypal funds. I used to use an unverified Paypal account but that's prone to being frozen when there's so much funds going in and out of your account. You don't want that to happen to your account, it takes 180 days (6 months) to get unfrozen.
You can also just use Purse.io so you can buy something from the Internet directly with your bitcoins. They are even giving discounts (15% discount) to bitcoin users.
Honestly there's a lot of workaround and the government will be just plain dumb to ban bitcoins. Bitcoin greatly helps some individuals and that makes the economy grow. As long as crypto isn't the reason why the economy is so messed-up, I don't see any point in banning it. They are just missing out. Bitcoin users are mostly tech savvy people. They are always in front of their computer and the workarounds that I have mentioned can easily be done by anyone of us. The ones that don't know how will be forced to learn it.