The market for external graphics cards seems to be growing exponentially this year with announcements left and right. The latest is a miniature eGPU dock from Zotac able to accept graphics cards of up to 22 cm length with a launch date no earlier than Q4 2017.
https://www.notebookcheck.net/Zotac-shows-off-its-own-classy-eGPU-Thunderbolt-3-docking-station.225228.0.html
$400... wow. Intel had made TB royalty free so I expect the price will sky fall soon.
I believe it's less about the royalty fee and more an issue of tacit collusion in a relatively niche tech-industry. The prices will drop eventually, but not by a big margin.