Intel, for instance, has stopped including stock coolers for its unlocked Core i5, i7, and i9 processors for a while now. The general reasoning is that if you have the budget for a high-end chip, you most likely won't be using it with a stock cooler. However, a stock cooler still holds its value like when you need it to stand in the event that your aftermarket cooling solution fails and you need to RMA it. Unlike Intel, AMD might give its future Ryzen 9 3950X customers a choice to pick up the chip with the stock cooler or not.
The regular Ryzen 9 3950X, which is listed with the 100-100000051BOX OPN on AMD's website, comes with the fancy AMD Wraith Prism RGB cooler. The 16-core, 32-thread part is rated with a 105W TDP (thermal design power), so the Wraith Prism should be more than capable of keeping its operating temperatures under control.
If you don't plan on using AMD's stock cooler, the Ryzen 9 3950X that comes without the Wraith Prism cooler carries the 100-100000051WOF OPN, where the "WOF" suffix means without a fan.
AMD has already revealed that the Ryzen 9 3950X will have a $749 MSRP. It'll be interesting to see how the chipmaker prices the Ryzen 9 3950X without the Wraith Prism cooler. If the price difference is significant enough, consumers would definitely opt for the latter. Meanwhile, a Chinese retailer has listed the Ryzen 9 3950X that doesn't come with the cooler for 6,380 HKD (Hong Kong Dollars), which roughly translates to $814.
As per usual for these types of listings, these could just be placeholder values, so take the pricing with a grain of salt.