Embracing the FUD early, I see. You do realize they make SSDs for laptops, right? I have 2 in my laptop right now. Heat is relative when discussing electronics, and both my laptop and the PS5 already have fairly hot components in them. The fan speed will increase because of the SSD bay, but I doubt it's going to be a massive increase in speed, unless they simply designed the SSD bay cooling poorly. Given the size of the vents going into it, I assume that they didn't expect it to generate a massive amount of heat, so I wouldn't expect the fan speed to increase significantly.
Also, you can also just not get extra drive. Given that costs scale much better on PC components than proprietary parts, the Sony solution should prove to be the best bang for buck long-term. PS5 owners will have the advantage of buying units that sell to PS5 owners and PC owners combined, while the XSX solution will depend largely on the Xbox ecosystem to scale production costs.