In fact, the blockchain does not require cryptocurrency as a dependency, because blockchain products do not rely solely on cryptocurrencies as a payment method!
Yes, Blockchain can be used for various purposes, but when it comes to making payments/transactions, then you need cryptocurrency to do that, as long as its Blockchain we are talking about. Unless you mean for other things such as message encryption like someone once said. Also read on Forbes that it can be used in voting, dont really know how that works, and there are still a lot of things it can be used for.