The billion dollar idea at EOS is to build a worldwide blockchain operating system for industrial scale decentralized applications or DApps.
If that succeeds, EOS would be worth big money because it would the blockchain to be used like the internet. Present-day blockchains simply lack the size, speed, and capacity to operate complex and gigantic programs or platforms.
That would not be possible with the present blockchain ecosystems like Ethereum. It might be possible with something like EOS if the claims about it are true.
Beyond that it would be possible to offer digital services like banking, insurance, and platforms for freelance work through the blockchain. Workcoin is already building such a platform on EOS’s ecosystem.