All these public companies run centralized businesses. If blockchain technology is adopted, won't they all eventually go out of business to be replaced with decentralized systems that run on the blockchain?
Nah.
First of all, decentralized solutions rarely more economically viable than centralized ones, especially since most consumers still care more about convenience than about ideals such as decentralization or even privacy.
Secondly, even in case of a decentralized blockchain revolution most companies will simply find a way to build their businesses on top.