When we talk about legalization of cryptocurrencies across the world, it is yet to be confirmed that all countries will be able to adapt to its usage. All of them have their own issues in regards to the currency use. I believe its not possible for cryptocurrency to become completely legalized worldwide, considering its current position in the market.
Only the nations where the governments have the intelligence to understand the benefits of Bitcoin will try to legalize crypto-currency. On the other hand, in the third world nations, the aim of the governments is to enslave the citizens. So we can't expect them to make BTC legal.
So cryptography is the coolest way to keep information securely,Even Institutional information...I hope Countries will start to use even blockchain for their institutional purposes,Which for me means tendence,Tendence of cryptocurrencies,Yes I know that blockchain doesn't mean cryptocurrencies but they are very close to each other and if countries implement this they will also start using cryptocurrencies...For example in my country,Goverment has already implemented blockchain to register property and to keep this registration documents,At the same time people started to use cryptocurrencies for their special purposes...So what you said is right,at the same time I hope that all countries will make it legal because of its profitable nature.