Where Season #4 Goes
I think there are going to be storylines for the 4th season.
One of which could be Etienne's death.. he was more lucid than ever prior to Juliette returning home and suddenly he dies, it was easily explained, but they said they will do an autopsy, so it could end up turning into some kind of mess, especially if Juliette runs off to the US to marry Noah.. and Sabine getting upset with her father for not realizing she was there and when she was referring to her as if she was not in the room. Could be the main storyline.
I think it is time for Luisa to have an affair and this might be a way to get Max back in the storyline. Luisa is upset and can't compete with Alison's backstory with Cole and runs into Max at some fundraising event that Max is running. Meanwhile Cole and Alison have on/off storyline.
The Helen storyline could easily be that the doctor turns out to be gay, there is not much know about the doctor's past and why would that guy be 40 something and still single, turns out he is gay and that is the mystery about him.
They have more characters now and maybe they can introduce a new love interest for Alison, perhaps a younger guy that becomes a freeloader.
Noah has a great season with his kids and Juliette, until they accuse him of killing Etienne..
There is a 4th season in there.