Update on this: German car magazine Auto Bild told me that its a Muletto based on the Zafira. They said they have their own pictures of it but they haven't released any pictures of that car yet. So i guess they are still trying to figure out what it is.

Combo = Can be ruled out, will share its base with Peugeot Bipper)
Bigger Van / SUV (BMW X7 Opponent) = The Mule didn't look bigger
next Opel Zafira = maybe

"Muletto" is what we call if the prototype has the visual appearance of an existing model, but something is odd: Bigger fenders, longer wheelbase or more ride height for example.