Even use case is not a guarantee of success. In my opinion the real use case is when a blockchain product gets adopted by a big company and is integrated in their solution. Till now, I haven't seem a lot of such projects, so why should Horizon have future?
Agree, there are still many crypto that have not been used. Among the many cryptos on the market, bitcoin is a crypto that is often used for transactions at merchants and peer to peer so I think bitcoin is the most useful crypto because it can be accepted anywhere