What will happen if all 21 Million BTC are mined? Or 20.999.999....
Who confirms transactions then?
How high will be fees?
Where they put the transactions? They have to find a new block for this as far as I know.
Would be nice if someone could explain this.
Mining will need to continue in order to confirm transactions. Miners will still need to be paid so their payment will need to come solely from fees. You can imagine that fees will need to be higher than they are now but it will be a gradual process as mining gets harder. It will probably be the end of the century before all Bitcoins are mined so we wont be around to see that happen anyway.