In practice, it's still speculation for a very long time. The speculation is over how much it will grow. Building a blockchain to do Y may demonstrate it can do Y, but from a value perspective, that is little more than a proof of concept until it demonstrates that it can grow large and attract a large amount users and economic value. It's barely one step forward from pure hype, and if the proof of concept demonstrates some problems with the concept or growth potential, that's a negative not a positive. It's not a given that such a proof-of-concept will be a negative in this way, but in practice many are, for various reasons, some totally legitimate (like most high risk experimental ventures fail, but that doesn't mean trying them was a bad idea) and some not (naked hype and fraud).