EDIT: I’m trying to draw a comparison between the availability dates (and where the companies are now), not the start of production (and their development velocity). Including the announcement date was probably a red herring.
Making a chip and making competitive chip are two different things.
When Nvidia enters the market with specialized chip it's likely on completely another level in bandwidth, energy consumption and price per flop performance. They have so much more experience with this.
* https://drive.google.com/file/d/0Bx4hafXDDq2EMzRNcy1vSUxtcEk...
* https://blogs.nvidia.com/blog/2017/04/10/ai-drives-rise-acce...
But without the data and not doing higher layers of the stack how can Nvidia create a product that is competitive with the TPUs for inference?
But also Google is already doing the 2nd generation of the TPUs and would expect a third.
The data of chips coming from 3rd parties are probably numbered.
The dynamics of the industry changed where now the companies that are buying the chips have skin in the game with the cost of running the chips. Versus the old days Intel sold a chip to Dell who then sold it to someone else.
It just makes sense for Google to do their own silicon at this point as saves them a ton of money.
But also Google has the data to improve the chip that Nvidia just does not have.
Developing a new high performance microarchitecture for GPU or CPU is complex task. A new clean sheet design architecture takes 5-7 years even for teams that have been doing it constantly for decades in Intel, AMD, ARM or Nvidia. This includes optimizing the design into process technology, yield, etc. and integrating memory architectures. Then there is economies of scale and price points.
Nvidia's Volta microarchitecture design started 2013, launch was December 2017
AMD's zen CPU architecture design started 2012 and CPU was out 2017.