Response here
You are saying that you could create a money that has no other use than being money. The only value it has is received through the subjective allocation of value by the parties involved in the trade. You would have to get everyone to change their subjective value towards this money. That is unlikely to happen and there would be a lot of people trying to convince people to use their money.
But surely companies like visa and mastercard are the key to a digital currency that is not national or international. They already have the means to create competing currencies, those organisations in combination with a paypal type organisation that could directly receive your salary by means of BACS. But you would definitely struggle to convince everyone that your money is worth what it is. Over time it could improve but at what cost to your money?
When i use national and international i am referring to a national currency and an international currency. Not a currency that is not attached to nationalism, but can be used internationally or nationally.