The best way to ascertain this is to look at the skills being hired for by the companies.

I use indeed, you might have another you like:

http://www.indeed.com/jobs?q=blockchain&l=

Click on a few to see the kind of skills you need. I am pretty sure this is more useful than our guesses.

Here is what IBM looks for in a block chain developer (whatever else you want to say about large companies, they put a lot of thought into the description):

3+ years of experience as a backend developer

Experience with Blockchain daemons such as Bitcoind and/or Stellar Core

Strong proficiency with Node.js, Java, and Golang ecosystems

Understanding the nature of asynchronous programming and its quirks

Understanding accessibility and security compliance

User authentication and authorization between multiple systems, servers, and environments

Integration of multiple data sources and databases into one system

Understanding fundamental design principles behind a scalable application

Understanding differences between multiple delivery platforms, such as mobile with API backends vs. desktop applications, and optimizing output to match the specific platform

Creating NoSQL database schemas that represent and support business processes

Implementing automated testing platforms and unit tests Proficient understanding of code versioning tools, such as Git

Experience with other languages such as: C++, Kotlin, and/or python