Let's review those assumptions. If "whole vehicle life" = 24/7 for 8 weeks, that is 1,344 hours of operating time.
In one hypothetical example, let's say an owner makes a couple trips around town during the week, goes camping on the weekend, and every other month takes an extended trip in the Defender. So for an average month, maybe the vehicle gets 10 hours of use per week with an extra 12 hours thrown in every now and then for a long term average of 16 hours/month. That equals 192 operating hours per year. At that rate, the owner hits 1,344 hours of operating time - the "whole vehicle life" - at 7 years. From the distance perspective, however, an average annual mileage of 15,000 seems about right. Some people drive less, others more, but that much mileage on a 10-year old vehicle would not be unusual.
My Range Rover is 25 years old and still going strong at 184,000 miles. I would not consider it anywhere close to reaching the end of its "whole vehicle life". Hell, I have a friend who drives three Series 1 Rovers, the youngest of which is 62 years old. Engineering a vehicle for only ten years of life sounds like a failure of vision. Maybe there is a technical definition associated with that or some engineering standard I'm not aware of, but I would hope that LR designed the new Defender with longevity as an objective. In some ways they already have with their other vehicles. If you buy a 2009 L322 Range Rover today, it's probably in much better shape than a 1999 D2 would have been in 2009.