It was in March 2015, that Google made the announcement of deprecation of various geo-products that included Google Earth Enterprise (GEE). And now, from March 2017 Google Earth Enterprise is going Open Source.
Google made the announcement that around 470,000+ lines of code of all the GEE products ─ GEE Fusion, GEE Server, and GEE Portable Server source code will be available on GitHub under the Apache2 license.
With this move, Google is expecting the GEE customers to use Google Cloud Platform (GCP) instead of legacy on-premises enterprise servers to run their GEE instances. Customers can still run the software in disconnected environments, but they might not expect the scalability of processing large imagery or terrain assets.
Here are some additional resources on Google Earth Enterprise featuring Mike Evanoff, Geospatial Engineer, Google