KLM Airlines is looking at in-wing seating in order to increase efficiency. Air travel accounts for a significant number of greenhouse gas emissions, being able to transport more people at once would reduce the number of flights needed as well as being more cost effective for the airline. This model would be 20% more fuel efficient than its Airbus A350 counterpart. The 20% reduction in fuel used on a global scale would have a very large impact on reducing emissions from air travel.
The airline is not looking to immediately roll out the in-wing seating planes, a rough estimate is that the planes could be ready between 2040 and 2050. However, the Airline has stated that testing will start on scale models this year.