> While PyTorch is obviously the future in the short term

Well, that's not obvious for me. The metrics do not support the death of Keras / TF (https://twitter.com/fchollet/status/1614322127460782087)

François Chollet's Deep Learning with Python is arguably the best book on the topic and teaches people using Keras / TF2. The Keras documentation is excellent as well, and in the long run it will matter. Personally I prefer the way the Keras / TF2 APIs work to PyTorch as well.

Also, I am pretty sure a JAX backend is coming to Keras, and there is TF Lite...

I cannot make a prediction as to which stack will dominate in five years.