The Bitcoin network is not in anyway like paypal or VISA, it is very similar to central banks issue moneys in big blocks and distribute them to the society. Just like the FED never issue credit cards, it is a waste of resource to use bitcoin to do micro payments, and in daily life, people really want to spend the fiat money first

Bitcoin won't replace fiat money, since their usage don't overlap: Fiat money is for spending, its value drops each passing year, and bitcoin is for saving, its value rises each passing year

Bitcoin is an unique addition to existing financial world and it will be welcomed by all the existing players, since it has the highest credibility on the planet and will be regarded as the most trustworthy store of value

If there is no cost to operate the bitcoin network, then bitcoin can also carry out  the mission of micro payments, but when the network traffic and computing power is a limited resource, there should be a focus on its major usage