diligent1,
The reason that 2019 will be the last version to offer the tooling is because the Application Insights team is planning on deprecating multi step web tests completely. The support life cycle for a Visual Studio version is 5 years, so the tooling will be
supported until 2024. You can read about the current situation in this Github thread: https://github.com/MicrosoftDocs/azure-docs/issues/26050#issuecomment-468814101
To summarize, the product team is currently recommending that people make use of multi step web tests as they have not yet created a replacement solution and there
will be a minimum of a 1 year overlap between the new method and the existing tests.
If you would like to create a solution that will last beyond this situation, then you can build your own tests and use the trackAvailibility() endpoint to send the information to Application Insights.