yes it is extremely hard. they've had prototypes of Polaris and Vega that were distinctly not ready for prime time with latency issues. the "Infinity Fabric" 2nd gen has proven it's value as an interpolater but no controller IC has been fabbed smaller than 14nm YET. as you know silicon "real estate" is at a premium and IC design is hard. "Arcturus" will be the optimized 7nm+ SoC, but we will see a "super-Navi" (multi-core) first as more than a proof of concept. there are some specific things i'm not able to say under restriction.