Not sure if anything has changed since then (2018), and this is by no means intended to discourage anybody from responding to the CFP, but Open Source Summit has historically been very difficult to get a talk accepted because it is a very popular conference hosted by the Linux Foundation.
Open Source Summit is also a developer & IT professional oriented conference that heavily favors highly technical topics, as opposed to application specific use cases. In recent years, there has also been criticism that the Linux Foundation has put too many sponsored talks on the conference schedule from big companies like Google, Microsoft, and Amazon.
As a data point, I (as one of the lead architects at Autoize) was unsuccessful submitting a talk (not Mautic related) to their Blockchain & Emerging Technologies track at Open Source Summit 2018 Vancouver - even though hundreds of people had liked the talk proposal on Twitter.
We’re interested in submitting. We’ll likely put something together about deploying Mautic in High Availability Kubernetes cluster as we recently completed this work. Probably something around commoditizing the cost of Marketing Automation and reducing the economic barriers to entry for institutions with large databases of contacts (as opposed to marketing automation solutions which require you pay per contact in the database).