I sincerely doubt that something like this will happen, when it comes to taxes, each country has its own rules. If EU member states want to create a favorable framework for investing in cryptocurrencies, then they already have several templates used by some EU member states. The point is that politicians in all countries do not have the same level of knowledge and will to regulate this way of investing - and this only contributes to uncertainty and confusion among investors.
Isn't there some judgment of the EU court on cryptocurrencies?
I think I read it somewhere but now I can't find it.
The ECJ has ruled that there is no value added tax imposed when Bitcoin is sold (C-264/14), thereby securing the foundation of Bitcoin being used similarly to stocks or fiat currencies.
When it comes to income tax, I think the member states are still pretty free in the rules they create.