The reason is that I believe electronics and software will become ever more important. Traditionally the German manufacturers have outsourced anything to do with software and even most of the electronics. They have no internal knowledge about software what so ever - every bit of software know-how is at the suppliers. That's why I think that at least some of the suppliers will be better off in the future than the manufacturers themselves.
And it is also a question of human resources. In the past and for a long time software developers at German car manufacturers have been looked down on by all the "real engineers" who are in charge. As a software dev you have been much better off at a supplier. This is changing but in my opinion it gives the suppliers a good head start on capable staff for software projects.
Outsourcing R&D was a typical MBA move since it meant they could keep a lot more money in their pockets and have the suppliers bid each other to the ground on price, however, this now means the suppliers have most of the cutting edge tech now and are free to sell it to other lower tier manufacturers which in the past had no resources for advanced tech.
So now you can have a Hyundai with the same tech as a Merc since they all have the same Bosch/Continental ECUs with some minor tweaks meaning the main selling point of the luxury brands is now the design, badge and perceived brand value rather than any proprietary tech.
This is what drove the major suppliers to halt R&D investments in Germany and expand massively in Eastern Europe in a quest to bring costs down and increase their success in the bids for future contracts.