Thank you for your answers.
Regarding the question Volvo vs Lexus, I totally agree. If this would have been a Lexus, I would have kept it without any hesitation.
Regarding concrete numbers: I have a quote for a nicely loaded GLE 350 or Volvo XC90 for 65k out of the door. For the Mercedes it is 3k below invoice, for the Volvo 5k Below MSRP. When I sell my s90 for 30k, I can finance either one of them for 470 per month (3.5% for 84 month).
If I would drive the Volvo for another 2 year and put 20k miles on it, it will be most probably worth between 16-18k in 2 years. That means I will loose 500 dollars per month if I keep it.
On the other hand, when I get a Mercedes and try to sell it in 3 years, I might be loosing 25-30k which will cost me 7-800 dollars per month.
So from mathematical point of view, it makes sense to keep the Volvo for another 2-4 years. I have another year of warranty and a mechanical breakdown insurance which costs me 80 bucks per month and that should take care of unforeseen issues.