You can't really buy a TPU, you have to buy the entire data center that includes the TPU plus the services and support. In Google Colab, I often don't prefer the TPU either because the documentation for the AI isn't made for it. While this could all change in the long term, I also don't see these changes in Google's long term strategy. There's also the problem with Google's graveyard which isn't mentioned in the long term of the original article. Combined with these factors, I'm still skeptical about Google's lead on AI.