Yes, that's correct - we will be adding the X-Pack code to the Elasticsearch (and Kibana/Logstash/Beats) repos, into a folder called
x-pack, to keep the code clearly separated. There will be no changes to the existing Apache 2.0-licensed code - we’re just adding the X-Pack code, under an Elastic License. We’re working on the details of the license language now and will publish it when it’s ready. This is a new model, and we’re taking a risk by opening the code of our commercial IP, but we are choosing to be more open as a company.
Today, we maintain X-Pack code in a separate, private repository because it’s closed source. But having the X-Pack code in separate repositories has real downsides - it means that issues, pull requests, builds, etc must be kept in sync across multiple repositories, for each branch, for each product, by each developer and all of our CI infrastructure. We took on that complexity within our engineering team because it was the only option with separate repositories. In opening the code, we’re taking the opportunity to simplify things dramatically, and that will make it easy for anyone to create and track issues, and contribute. By definition, this also means that we’ll be able to develop code more quickly, get feedback faster, and this ultimately allows us to make better products, which benefits everyone.
It’s important to note that there are free features in X-Pack - like Monitoring, grok debugger, etc. So a contribution to these features, like a new chart in the Monitoring UI, would be included in the free tier. I agree that there is little incentive for non-customers to contribute to Gold/Platinum features, but we are looking forward to the ability to directly collaborate with our customers on Github.