I find this type of product incredibly interesting — a muscular compact system with robust integrated graphics plus a pathway to make it into a powerful high-end gaming pc. I think the $500 price tag on that external GPU dock is the Achilles heel to this and all compatible systems. It makes so much sense that someone who is moderately curious about high-end gaming might buy a system like this, or a similar laptop with the idea that they're getting darn near the best money can buy for CPU/SSD/motherboard, plus some fairly decent graphics handling, while leaving the door open to adding a GPU later on. This scenario is completely derailed by the $500 price tag to the external GPU dock, though, which makes the price/performance ratio more top heavy than Dolly Parton.
I don't know what it is that makes the external GPU dock so expensive, but my hope is that price is just full of margin and that some competing products can deflate it down to sub-$250 where I imagine it belongs.