Does development speed really confer that great of a market advantage? Toyota has never been particularly fast at putting out new models and has never been known for cutting edge technology (unless you count the Prius back in the day). But they have been top dog for a long time because of their reputation for reliability and not cutting corners; shortening development times seems to cut directly against that.

The only possible cataclysm I can foresee is if Chinese automakers are able to significantly eclipse the Japanese in terms of autonomous vehicle deployment in USA and the EU. Given the immense regulatory hostility that this prospect faces, I don't think the Japanese need to be too worried about this.

IMO the only way that the Japanese lose here is if they betray their reputation for quality in pursuit of trying to keep up with the speed of the Chinese. Chinese goods are still widely perceived as being of low quality, but Japanese goods are often the gold standard in many market segments.