I don't get what's so difficult to do on-prem. Your target market on-prem all use Kafka as their event bus and either Mesos or Kubernetes as their execution fabric - what's so tricky about fitting into that?
You can of course do something like that yourself in your own infrastructure, but then every piece of software needs to support it somehow, you need to manage that event bus infrastructure and you most likely have to push those events in yourself.
And that kind of thing is already there, so the appeal that Serverless event driven systems in the cloud have (because the providers give you all of this out of the box) is much harder to achieve when you have to do that yourself.