Currently it's looking like Waymo's most viable competitors are in China, namely Pony.ai and Baidu's Apollo.

Even without competition it will be a long time before Waymo is operating in most American cities.

Assuming Chinese competitors get cut off as a "threat to national security", I'm sure Waymo would behave responsibility as a monopoly and won't be driving for a system that "accidentally" end with private car ownership being eroded along with public transport options in favour of their product.

It would be crazy if a self driving car company would undertake projects that undermine public transport, for example. Proposing mad things like vacuum pod trains to head off conventional HSR for example. Imagine!