For some reason I imagined "Express", whoops. Weird.
The nature of problem is the same though, except no chance of saving AAs. You can kill a fly with a sledgehammer if you want, it's a very popular hobby, but not exactly necessary. I've seen zero evidence that heat contributes to the failure of these consoles in any way. My experience is tainted since I live in Michigan and have air conditioning. Maybe people in the Malayasia and India have something to worry about.
Lack of use kills them more than anything. When I sold my US Duo after many many years it had a ton of hours on it because I never got bored of it. I always play my stuff. I only sold it when I had other PCE consoles and someone wanted my Duo.
In about five years, if your theories are correct, then we should be seeing the first wave of recaps starting to fail from the suposed heat problem. If mine are correct it will be a couple of decades. Hopefully I'll still be around then to school noobs about how running Emulators built into their cyber tats isn't the same as a CRT and how Victory Run isn't really worth $50,000 no matter how good it is.