this is for the dummies, they pay $650 for the NUC, $500 for Razer GPU Box and $650 for a 980 Ti (anything less is stupid to put in a $500 box). That gives you a total of $1800.
You forgot to add the cost of RAM, SSD, and OS, which brings it up from 1800 to $2150 !!!
Interestingly, I think your "this is for the dummies" comment is actually the appeal of this device.
Consider if you bought a smallish Mini-ITX system with integrated graphics and you later wanted to upgrade to high-end discrete graphics. At best, the upgrade path is to buy and install the new graphics card with all of the possible power, heat, and fitment issues that come with it. At worst, you buy a new case and PSU and transfer all of your components into it. Not a big deal for you and me, but a deal-breaker for the vast majority of PC users.
If you had bought a Skull Canyon, the path to high-end discrete graphics is the cost of the Razer Core and graphics card. At best the Razer Core comes with the graphics card already installed and the installation takes only seconds to plug in cables. At worst, you have to install the graphics card into the Razer Core, then plug in all the cables. I can see the appeal of that for a lot of people, and if those are people willing to pay the price, then I welcome them to the world of PC gaming.