Bitcoin may cause banks to disppear but it will take a long time. its possibility will be determined the level of acceptability in the world. And i know that for every country to accept it is not todays thing
Add it up that bitcoin is decentralized. I wonder how governments want a currency which they can't control most especially influential countries like United States and China. But for the benefit of everyone decentralization of monetary system is the best. This should lessen the influence of banks, rich countries and personalities on the world's financial system.
You were right up to a point (I made it blue).
No, bitcoin will improve their influence.
Let's think for a moment where are the major holders of bitcoin. Look at the nodes map.
Probably Africa and South America/ South Asia have less than 2% of the total coins mined.
BTC will just make the ones that can afford to buy now richer, it won't make the poor rich.
Today there is a noticeable trend especially in developed countries to minimize the amount of paper money in use. If this would happen in such extent that everybody would use only some kind of electronic payment (which is highly unlikely since some people don't want to use credit/debit cards for a number of reasons) then it might be possible. But as i already said, not likely.
14 countries in the EU have more virtual /electronic usage than cash transaction.
In 3 of them cash payments have gone below 10%.
It will happen, sooner than you think.
