Is the Upgrade Path in Zorin OS complete or does someone knows how it is looking right now
If you are meaning 16 to 16.1 - this happens during applying Software Updates. If you are speaking in terms of a rolling release to 17 I don't know.
Nobody knows, but when it is done I'm quite certain there will be an announcement of such. But chances are it will be announced closer to when the 17 update is actually coming.