I hear where you are coming from MH, but I've never had to repair anything on my Mk5 GTI for reasons other than general wear and tear. Not saying it would last 26 years, but looked after well and driven reasonably, even a modern car should do OK.
Not running a car past it's warranty period is a bit of a false economy though, and one of convenience as far as I'm concerned. Swapping your car after 3 years means losing a bit of money on trade in, and losing several thousand each year in depreciation on the new one. At the same time, the car that's over 3 years old would be depreciating at a much lower rate, and I highly doubt would cost the equivalent each year in maintenance and repair bills.
Apart from enjoying my car for its looks and performance, and not really liking the Mk6, it's why I was happy to keep it, and hope to do the same with my Mk7.