I wouldn't go with the Core X because you're paying extra for 100W Delivery. I'm not saying its a bad box, it looks nice. If it were a MacBook Pro (and it is compatible, haven't read up on this model) then I'd be all over it, but I wouldn't want to pay more for a beefy enclosure with power delivery.
I think my RX 580 should be adequate for some time but if I decide to upgrade to something a little nicer in a few years the PSUs are also upgradable on many models. If Nvidia blesses us with full eGPU compatibility over the next year, I have a 1080ti that I will drop in immediately.
Figure out your needs\wants, then find the most compatible card, then find a box to stuff it in.