I don't think it would be much noiser than a night train, especially if they work on the noise isolation of the berth.

On the mockups (http://www.airbus.com/newsroom/press-releases/en/2018/04/air...), it looks a bit like the Japanese pod hotels.

Depending on departure and arrival times of the plane, it could make sense to me. I have used night trains quite a lot and it works fine.