Just a quick note: I think the two can very easily be merged. Just by the fact that Design Thinking is a human centered approach and has value creation in it's heart. This is very easily translated into sustainable solutions. Specifically I would do some research into the Circular Economy. In short, this idea takes the leap "from ownership to value creation". So not owning a product, like a iPhone, but leasing it and handing it back to Apple when they have a new model. Apple then treats the old products as valuable resource with rich material to be used in new products... well something along those lines.. Just check it out :-)
Yes Arne, your note is very important! Liked! What I sometimes think is when we work in a organization try to see each new project about optic human for some employees can be difficult, first why they need break down a mindset or because design thinking is a discipline more expansible like behavior - been collaborative. So, when we try to the dimension sustainable this same optic looks like distante on projects. Is like we apply design thinking like initial process, but not on delivery products/services totally, blaming the culture.