That's for the Excel team to decide. My personal hope is that they'll offer as a base:
* Python 3
* Numpy, SciPy, Pandas, Matplotlib, Altair, ...
* Pythonic bindings for Excel APIs (sheets, etc etc)
* VSCode's Python Editor + Debugger built in
* Some sort of conda based env/pkg mgmt
* Right-click, "Open in Jupyter" (data/code)
* <your wish here>