Hasn't it be done already, with FSD (already accessible to hundreds of thousands of Tesla owners) and zero intervention?
IIRC, Tesla or Elon said the coast-to-coast thing is not a goal for the company anymore because they prefer to work the actual needs of the Tesla drivers, who bought and use the product already but don't do coast-to-coast. But FSD can definitely achieve this today (single stack for city and highway since v11.3), it's just a matter of reaching zero intervention (once or repeatedly).
There are so many zero-takeover drives published daily nowadays: https://www.youtube.com/@WholeMars/videos (some are 7h+ long: https://www.youtube.com/watch?v=sgAwKf9HCHU)
They're not so big that they can afford to pour a lot of money into it (and we've seen from Google, Uber and Tesla how slow the progress there is if you want a tech that works reliably in real life).
I hope they double down on what they're great at, and this announcement is a step in right direction (IMHO as an armchair analyst, I'm not in the industry).