What is the future of DevOps in the age of serverless?
Also serverless needs some infrastructure and for that you also need software components to develop and rollout. 

Beyond yet another website or application server I'd also think of energing advanced ecosystems related to:


Internet of things -  embedded systems and edge servers
Artificial intelligence and data engineering in distributed systems. Could be some ETL (extract, transform, load) stuff or training and logistics for machine learning models.
Gaming but also working in virtual environments.


So given the cloud market and these ecosystems will grow,  even if servetless would dominate, there will be a DevOps market, maybe smaller than now.

Otherwise it is in general very hard to predict how (IT) world and job market might look like in say 20 years.