>Which ones?
ChainLink, as this project is aiming to incorporate outside data into the blockchain and smart contracts. This has plenty of real world use cases. This could be what the internet is to a computer, but for blockchain. Zen Protocol is also working on a similar idea, but they incorporate smart contracts into their project and have improved upon ETH's model a bit (not charging gas for failed contracts to name one example). I see no reason why this wouldn't be adopted if they can deliver.
Request Network, a project backed by this very website, is working to create a currency agnostic payment platform that may compete directly with PayPal and demands far less fees. There is a pretty incentive to adopt this over vendors listing individual currencies for payment methods, and everyone saves money due to lower fees.
RaiBlocks and ByteBall diverge from the blockchain and instead rely on DAG tech, and have extremely fast confirmation times because of this, and scale upward excellently. There is incentive to use these in the crypto space because transfer times and tx fees are too high, but we'll see how the outside world reacts.
Ripio Credit Network is working on making a decentralized lending platform to allow (currently) South Americans access to reasonable lending solutions, but I see this extending to a much larger global scope if successful. There is pretty clear incentive for adoption here, you can read about their potential customer base.
Just to name a few, I invite you to research a little more as a lot of these products are pretty amazing, and I'd be curious as to why you think the above are "worthless". But yes, adoption is the biggest concern. Personally, I don't see cryptocurrency ever going back to $0, the technology is better than existing models of centralized banking and middle men. Unless something comes along that disrupts the disruptor, I think it's here to stay for the forseeable future.