There are already some novel applications of this. It is extremely useful to use Google's screening service for unknown numbers that might be a call I'm expecting from a new number. I can't recall the last time I actually listened to a voicemail. I know that at least voicemail transcription works elsewhere, and I can't speak to how well, but I do know that on the Pixel, transcription is really quite impressively accurate.
I'm sure it's not much different than the test shown in the twitter post, but I've enjoyed calling myself from another phone and then screening the call and doing my best micro machines guy fast-talking impression just to see how well it really can transcribe conversation at real-time speeds.