Yes, I am looking forward to seeing this on some engineering disaster channel in few years.

Wait, what? You want to see a disaster occur?

I'm reading that to mean a disaster like the Brandenburg airport in Berlin

Often these are less about actual disasters and more like the brandenburg airport, where a lot of money (and more than originally expected) is spent for very little gains.

Brandenburg airport, I think we might watch the same podcast (with slides).

No, the commenter believes a disaster will occur and is looking forward to seeing evidence that their predictive ability is accurate.

The context makes it clear that the parent means the car tunnel itself is the disaster. The video on the disaster is going to discuss why the tunnel is a failure. The project will be a disaster.

Doing trains badly is better than not doing underground trains (or any trains) at all.

I'd argue that (a), it's not, and (b) we're not doing trains at all. It's just another road for cars, this one's just underground.

It is interesting to me that so many are hung up on form factor. It is like is has gotta look like a traditional NYC or London subway train (complete with gum stuck under the seat I expect) or it can't possibly be any good. It should just be about speed and amortized cost per unit distance.

The bulk of the cost of building a subway is in the tunnel construction. Could as well retrofit the tunnels with tracks for real trains later, when everyone except Elon realizes how little sense the original idea makes.

Don't know how easy that will be. Tunnels built for cars can have much tighter turns than a train/subway tunnel. Unless the tunnels are being planned with future conversion in mind they might need significant rework to be able to carry a train.