Bitcoin can lead the digital world as it is a powerful payment method.
It can not replace the fiat money ever, but it can be one of the top (digital) currencies in the world.
What is needed for bitcoin to become more popular is when big stores implement bitcoin and people will gradually pay attention to bitcoin.
I dont agree with you.

I think bitcoin someday can replace fiat money, because today everyone have smartphone and bitcoin more easy to use in mobile.

The folks at Circle seem to believe that more people will transfer USD via their mobile than BTC, so they are now promoting the blockchain and kind of pushing the mentioning of bitcoin itself to the back burner - even though they are using actual bitcoins to transfer USD and other fiat currencies