I'd say its not about blockchain as a tech - there are other of kind. It's about trust-less, open, permission-less and border-less networks of consensus.
And it all will be huge. But will be steem or BTC, or any other project we using now, a considerable part of it? THAT is a million $ question!
Very true although, at this point, Blockchain is what fits your description. There might be other iterations of technology that follow which will also serve what is discussed here.