We all know that bitcoins price changes quickly because of its demand So if some online shop sells products and pricing it in bitcoin,
How can we price it ? Should the price change also like btc?
You can start to price thing in BTC once everyone uses BTC and there is no need to convert your BTC to fiat at any point to pay for something you might need.
If the store owner can buy the product from the supplier with BTC, and that supplier can buy materials with BTC, and those suppliers can pay for their food, housing, utilities, etc., using Bitcoin, then you can start to price things in Bitcoin.
Essentially an entire financial system overhaul.