I've been involved in pioneering Jenkins, maintaining Jenkins, and using Jenkins for the past 7 or so years off and on in different roles, often that of the Jenkins admin. The original article has a lot of good feedback that I'd suggest addressing; it hits a lot of the pain points I've had in the deploys I've had my hands in.

For myself, I'd prioritize -

An indepth improvement of the Config as Code system as applied to Kubernetes, both for management of the config and of relevant plugins.

Plugin compatibility and management of plugins. It's not... smooth.