however, many are pessimistic that Bitcoin will be able to shift conventional currencies both at the local and global level, will there be a miracle of bitcoin to shift conventional currencies
It seems like you need to reach the bitcoin whitepaper again. Bitcoin can be considered as a new way for people to get out from the centralized economic system related to the fiat money as a currency that is fully controlled by the government. that gives so many restrictions for the users that were not able to be free from the intervention created by the regulators.
Bitcoin and conventional currency will co-exist. A replacement can be made by bitcoin as a digital currency but when it comes to the fiat money in real life and then fiat will always become fiat.
Bitcoin has become a new standard in the digital currency right now.