I wonder if this will curtail the effort to implement TensorFlow in Swift, turtles all the way down?

That would be a shame. Python ecosystem with TensorFlow, PyTorch, mxnet, etc. has been good for rapid progress but I think we need something better to break out of just using deep learning. This needs a hackable infrastructure. I personally don't have the skill to hack the C++ TensorFlow core.

I think a new ecosystem based on Swift, TensorFlow, and future tools and platforms makes some good sense.

An alternative would be a similar hackable infrastructure based around the Julia language, which is also very good.