The country that has the highest tax on cryptocurrency was stated in the earlier reply, so I would like to focus on the possibility of these countries lowering the taxes.  I believe if there is no special event that will happen, the tax will possibly stay as it is.  If there are programs or special events, like attracting crypto enthusiast investors in their country, they may lower the taxes to make it more appealing to these investors. 

We all know that the government often lowers taxes or even gives exemptions if it thinks it will benefit their country in the long run, so I believe the possibility of these high-taxing countries on crypto to lower their tax requirement is more likely dependent on the future crypto programs or plans.