Unfortunately you're not allowed to ship these files with your game. They have to stream directly from Google's servers for each user (caching is allowed as long as you follow standard caching rules).
But that has been around for an age as well - it just wasn't available via an API.
Bing came out with 3D buildings after Google did and the coverage was a small fraction of that Google had and hasn't increased very much in the intervening years.
(I hope apps will offer both as data sources and maybe select the one with the best fidelity for a given region)