Blockchain gonna be base protocol (like TCP IP) and Dapps built on top of it.
So theoretically ALL businesses can be rebuilt and run on top of blockchain technology.
But its long time ahead, now imo best usecases for blockchain:
1. C2C platform: something like central stock exchange can be replaced totally by blockchain.
2. robotics and sharing economy: you have your own robots/device but not utilize its maximum capacity, you can allow others to rent this robot with a given fee, and all of those stuff should be autonomous and transparent via smart contract, no need of a platform like Uberobotics for it:)