I worked in second-hand shops and managed 1 for some years. I also game hunt a lot and finding a white system is rarer. Japanese shops it's usually better. Except it's a mixed bag on Super Famicoms. Heat and/or UV light reacts to a chemical in the plastic. White Saturns pop up a lot but every so often a yellow one creeps in. In the US tho games and systems are heavily abused. Missing inserts. Cases. Scratched discs. Yellowed systems abundant. Oddly one thing I saw a lot is Wii's were fine except the panel for Gamecube controllers turned yellow. Just the panel door. Then I don't even want to touch a smoker's system. That smell never gets out. One common issue with used consoles is dead bugs inside them. Cockroaches esp. The plastic yellowing mainly depends on how much heat or UV light it gets.
Somewhat unrelated but another issue with older electronics is those that had a rubberized surface. It deteriorates after a decade or so into a sticky gooey mess. An MS Zune from 2007 or some older Laptops or an OQO.
I would think the bigger concern would be how many of those outward curving edges are going to be cracked/sides completely broken off in the future. It just doesn't look to me like a product that is meant to last the test of time.
I've been wondering about the giant open venting on the top of the XBSX. How often will something get accidentally poured into the top of the case?
Then there's just the size and shape. How many people, kids especially, will try to sit on it when vertical, busting it off it's stand or worse?
Would have figured that MS had thought these possibilities through and built something more child/idiot proof.
MS did build a 'smaller PS5' that overheated, and PS4 'fixed' that by including 'jet engine powered' cooling, so, are we really shocked with these next gen designs?