Mine's a year 2000 C4 that has just turned 90K last week. Bought it with 30k on nine years ago, and even though it runs really well and owes me nothing, I think I will move it on next summer after a Continental trip we have planned.
My experience with cars that have gone past 100k, and I have owned a few, is that they require constant replacement and maintenance. I had a BMW with about 110k miles on that needed new piston rings, others that have required big end and bottom bearings replaced. Camshafts with the hardening worn away, refurbished carburettors etc. None of these actually let me down in any way, but to pass the MOTs it was necessary to have the work carried out.
The trade are a conservative lot (they are in it to make a living) and remember stories like the above from 100k cars. After all, they have to warrant a car they sell, so dependent on their
Insurance / warranty terms or their own personal views, they will not take risks.
This depresses the market which leave good pickings for private individuals who are prepared to live with this or are lucky with good high milers.
I have been looking for something different for a few years to replace my 996 (M6 V10, SL55, new Boxster GTS / Spyder), but after nine years I think I'm due a change and at 92 - 93k by then, the time may be right.