There must be some cool application for this but I can't think of what. I guess computing shadows and things like that but we often already have 3d buildings (though maybe not for rural areas like this does).

I did a similar project as a toy many years ago: https://nbelakovski.github.io/topography_neural_net/

In my case I just used it as a vehicle for learning about neural networks. I couldn't really think of a compelling use case. I wonder if the author of this article of the authors of the model have found one.

Does this mean that Google Earth may get 3D models for more world cities? As of today they only have 3D for a limited number of cities, mostly from wealthy countries. Also, would Microsoft Flight Simulator also get more accurate 3D cities? And what about terrain? Google Earth uses mostly guesses to gauge the height of rural terrain like mountains.

This blog is great! I follow him since long time and I always find really interesting contents. Kudos to the author