I am most interested in making py.exe follow PEP 514 and look up tags. Given this, we could register builds as "PythonCore\Dev" and then use "py.exe -dev" to run the most recent build. At worst, we only have one lingering registration (and a positive - it would be available to any tools that follow PEP 514 to locate Python installs).

Alternatively, it could go to "PythonDev\..." and we have another way to look it up.

The default tags used to register Python deliberately match the py.exe launcher (e.g. "3.6" and "3.6-32", though it now also supports "3.6-64" to prevent fallback to the 32-bit interpreter). This should make it *nearly* a non-issue to change the launcher to look up Tags rather than versions. Probably needs a prototype to see just how bad it would be - I haven't had time to do it.