The Realtime API deprecation page says it will be possible to use: https://developers.google.com/drive/v2/reference/realtime/get even after the RealTime API is shot down.
Will it also be possible to update real time documents using this? https://developers.google.com/drive/v2/reference/realtime/update
As far as I understand these are only exports/imports so it should work even after the RealTime API infrastructure is gone.