I don't know that the ML community necessarily _needs_ a better language than Python for scripting ML model training. Python is decent for scripting, a lot of people are pretty happy with it. Model training scripts are pretty short anyway, so whatever language you write it in, it's just a few function calls. Most of the work is in cleaning and feature engineering the data up front.
Perhaps a more interesting question is whether the ML community needs a better language than C++ for _implementing_ ML packages. TensorFlow, PyTorch, CNTK, ONNX, all this stuff is implemented in C++ with Python bindings and wrappers. If there was a better language for implementing the learning routines, could it help narrow the divide between the software engineers who build the tools, and the data scientists who use them?
Perhaps a more interesting question is whether the ML community needs a better language than C++ for _implementing_ ML packages. TensorFlow, PyTorch, CNTK, ONNX, all this stuff is implemented in C++ with Python bindings and wrappers. If there was a better language for implementing the learning routines, could it help narrow the divide between the software engineers who build the tools, and the data scientists who use them?