Every console stops selling eventually, sometimes quickly, but it's important to note that that's not strictly "cliff theory".
The whole meme of "Switch sales will fall off a cliff" was not that Switch would someday come to a rapid halt, but specifically that its sales would collapse early or in the prime of its life; it started with "Switch sales will fall off a cliff in 2018" which then became "Switch sales will fall off a cliff in 2019" and so on and so forth.
Switch sales dropping off once its successor comes out isn't "cliff theory".







