Blockchain is the new PKI
I used to be a consultant at one of the Big 4 firms and one of my areas of specialism was asymmetric key cryptography, Public Key Infrastructures and Trusted Third Parties. It was a fascinating field. It was technically challenging, which I loved and there was a huge number of potential uses.
Fortunately, I went on to specialise in information security more generally because despite all the hype, PKI never took off in the way that many people (including me) hoped.
The issue with a lot of crypto technology is that the underlying principles are often elegant and reasonably easy to explain as long as you don't get into the maths. The same could not be said for the implementation. Cryptography is often extremely hard to implement in such a way as not to break anything. The implementation details mattered and in the long run, they were very often a major stumbling block when going from a simple POC to a full implementation.
Blockchain looks very similar to PKI from where I'm sitting.