It was a bit underreported but one of the interesting things about the upcoming Ryzen Threadripper is that AMD decided to adopt LGA (land grid array) rather than the PGA (pin grid array) that the company has used for most of its CPUs for the past two decades.
AMD probably did this because LGA enables higher pin density, Threadripper is already a huge CPU and making it with 4,094 pins would make it absolutely huge. Another great benefit of LGA is that it makes the CPUs easier to handle, with PGA there's always the risk of bending pins.
So, why didn’t AMD go LGA sooner? Well… there’s nothing to actually back up the fact that future AMD chips will all be LGA, so don’t expect it to happen even with Zen2. LGA designs are more expensive to produce than PGA, which I’d have to imagine is the reason AMD has stuck with PGA for so long. But on a chip like Threadripper, with its 4,094 pins (3x Ryzen), LGA was likely a requirement, rather than a “Meh, we might as well” kind of move. Threadripper is a massive chip, after all, and with a tripling of the pins, the chance of accidental damage would be heightened.
Techgage also points out the socket itself on the ASUS X399 Zenith Extreme motherboard is secured with three screws that must be removed in order to install the CPU. Similarly, you will need a heavy duty cooling solution for Threadripper because the chip's integrated heatspreader (IHS) is much larger than even Intel's biggest offerings.
Cooler compatibility is definitely something to check if you're planning to upgrade to the X399 platform.
This means you will probably want a special heatsink designed specifically for X399, and those will probably cost more than what you're used to due to the small target market and the larger heatsink base size required for Threadripper's huge IHS.
Alternatively, it's also possible to use a heatsink that doesn't entirely cover the IHS. As long as the CPU dies are covered you should be OK with a cooler designed to handle at least 155W, but I think seeing a part of the IHS not covered by the heatsink just won't feel right.
In the above video, Steve does give us some good news about that problem: you won’t necessarily need a special cooler for Threadripper. As long as the cooler you do have covers the CPU’s dies, the IHS’ copper design would spread heat efficiently enough where the perimeter of the IHS being exposed wouldn’t matter. Ideally, you’d still cover the entirety of the IHS, but it’s nice to know that it’s not going to be required – as long as the cooler you do choose is spec’d to handle at least 155W.