I agree with what brian kelly has to say. Adoption rate is still too low. A new security has been created in a way in the form of tokens. There is no regulation.
On the development front, bitcoin, after 10 years is yet to see scaled adoption or a use case. We are still seeing innovation to increase its use case. For other projects, their tokens are valued at billions but no product out or userbase for most of them, the actual equity value may be a lot lower.
And so far companies are only talking about exploring blockchain, it will be a bubble when santander's dubious ripple app becomes mainstream or when mastercard claims to be rolling out decentralised services. Or when the use of 'blockchain', as incorrectly defined by most centralised companies, leads to blockchain products being rolled out left right & centre.
So far we are nowhere close to a bubble. The internet and www of the future is still in early stage development.