Things Docker can/does charge for and could do very well with.
- Support: Businesses are happy to pay maintenance contracts for fixed LTS versions of Docker which is their EE product.
- Kube: Docker has pivoted their UCP product into a turnkey on-prem Kubernetes distribution. Plenty of room in that space to grow.
- Registry; You wouldn't run random images from DockerHub in production, right? Similar to Red Hat's product in this space there's a lot of money to be made in having officially supported images. Images with a pedigree, aduit trail, CVE reporting, yada yada. Partner with Canonical and since it's way easier to do this when you already have distro maintainers and you have a solid RH competitor that devs will like more.
- Security: Audit your images that have been sitting around and not updated in ages.
- Hosting: They'll be one of many but there's plenty of space in providing some ergonomics compared to Google/AWS's offerings.