If all countries accept crypto, I think, the altcoin and Bitcoin that have been circulating will decrease, it will cause the price of coins to go up, we can see the Bitcoin legality map and some articles about countries that accept crypto as a means of payment and adopt blockchain technology
1. MaltaMalta is known as “blockchain island”, and have taken legal steps to show it. Malta for example is the first place where a decentralized bank and stock exchange will likely take place. On July 4, 2018, that the Parliament of Malta approved a regulatory framework for blockchain technology, making Malta one of the most ‘blockchain-friendly’ countries in the world.
2. Switzerland Zug in Switzerland is known as “Crypto Valley”, that’s not by accident. Switzerland is known as a crypto-friendly nation due to both its establishment of a virtual currency hub, “crypto valley,” in Zug and its status as a tax-free haven for crypto investors. DFINITY have a team there in their attempt to marry Silicon and Crypto Valley to take on Ethereum to build a next-gen world-computer.
3. Estonia Smaller countries have a distinct advantage to adapt rapidly to a changing world, and Estonia is a perfect example with blockchain. Estonia has been making strides to encourage blockchain technology that interweaves with its economy
4. JapanJapan has always been months if not years ahead of most places in Bitcoin and crypto adoption. Japan is among the largest Bitcoin traders and some of its retail stores already accept Bitcoin. According to a Nikkei report cited in a note by Masao Muraki, a global financial strategist at Deutsche Bank, around 40% of bitcoin trading in Q4 2017 was conducted in yen. It’s not by accident that the pseudonym of “Satoshi Nakamoto” is Japanese. Japan is a Bitcoin-native country unlike any other.
5.ChinaDon’t let the crypto ban and crypto mining ban fool you, China is among the most forward-thinking countries with regards to the Government’s own adoption via its Central Bank of fiat to blockchain. China is also known for having thousands of blockchain based startups. Banking consortiums in China are also starting to rally around blockchain. On top of this, Government is very pro blockchain and AI; and actively supports its own top cryptocurrency and smart contract platforms such as NEO, VeChain, Qtum, TRON and others.
source:
https://medium.com/futuresin/top-8-crypto-blockchain-countries-2c526e00e951source:
https://en.wikipedia.org/wiki/Legality_of_bitcoin_by_country_or_territory