...could be a marketing nightmare selling expensive zooms coming out at the same time (approx) with overlapping focal lengths..
Yeah, that makes sense. I'm sure VW and Chrysler are just as worried about the marketing nightmare of internal competition from their Porsche and Mercedes subsidiaries. Just like the 100-400 vs. 200-400, there's bound to be a lot of overlap in the customer base.
Off topic, but Mercedes never was a subsidiary of Chrysler. Daimler bought 92% of Chrysler's shares (I believe in 2003?) and then the company was named DaimlerChrysler, but they split in 2007. Daimler (and Mercedes as well as it is only a brand of Daimler) are now completely separated from Chrysler, just as they used to be before 2003.
Besides of that, I completely agree with your opinion.
I worked there in 1998 and it was DaimlerChrysler. Jurgen Shcrempp was the Head boy form the EU.... They might have been bought a year or two earlier.