How can that ever be a thing? We KNOW 4680s work, as there are model Ys with them in. AFAIK the only issue is yield. If its physically possible to create 4680s that are fine in current vehicles, then I have 100% faith in Tesla, or indeed anyone, working out the production process so its super-high yield.
I agree that 4680s do seem to be ramping slower than hoped, but frankly as an investor that just tells me that it will be harder for competitors to copy Teslas work in this area.
I'd be worried if there were no 4680 model Y's already, but we know there are. And in any case, they are not crucial to model 3 or model Y anyway. My 2022 model Y performance has 2170s and its an amazing beast of a car. Tesla got to #1 selling car in the world without 4680s.