When updating to macOS Catalina will the default Python installation get removed from my system?

Solution 1:

From Xcode 11 Beta Release Notes:

Scripting language runtimes such as Python, Ruby, and Perl are included in macOS for compatibility with legacy software. In future versions of macOS, scripting language runtimes won’t be available by default, and may require you to install an additional package. If your software depends on scripting languages, it’s recommended that you bundle the runtime within the app. (49764202)

So in Catalina these runtimes will still be available.

Also, from the same document

Use of Python 2.7 isn’t recommended. This version is included in macOS for compatibility with legacy software. Future versions of macOS won’t include Python 2.7. Instead, it’s recommended that you run python3 in Terminal. (51097165)

Solution 2:

I installed MacOS Catalina Beta and it was packaged with scripting languages like python (2.7) and ruby. Python3 was not available.

So probably they might remove it in the next major release (10.16) or they might remove it in the stable version of 10.15. In the former case, everything would function as expected, I believe.