While XPages is no longer a future investment for server side web development for Domino.
Domino then does not have a server side web application framework which leaves it to be a back end NoSQL database.
Developers who have invested heavily in software engineering will continue to work in Java or C# and adopt tools from either ecosystem.
Over the years during Domino's decline to Microsoft, many Domino developers changed careers to work in C#. ASP.NET Core is a SpringBoot version for C# with Microsoft's partnership with Pivotal (makers of SpringBoot).
Imagine a Ex-Domino developer or a current Domino developer moving to ASP.NET Core to replace XPages has a option for Domino DB Connector (one exists for IBM DB2) in VisualStudio? How exciting can that be and the interest sparked by the developer.
If there is no connector, then Domino appears to be that island that is not friendly with other ecosystems by both Java and C# developers. Having this connector will slow down Domino migrations especially now that there will be no evolution with server side web development in XPages.
ASP.NET Core is platform agnostic in every way and cloud ready. IBM Cloud / Bluemix supports it.
Let's co-exist with 'thriving' ecosystems.
https://docs.microsoft.com/en-us/ef/core/providers/
Look, Microsoft is winning over customers by having a excellent thought out API for Java and excellent documentation https://github.com/OfficeDev/ews-java-api/wiki/Getting-Started-Guide
https://cloud.ibm.com/docs/runtimes/dotnet?topic=Dotnet-dotnet_core#dotnet_core