Everybody was expecting Arcturus to be the high-end version of Navi and a true competitor for Nvidia's RTX 2080 / Ti gaming GPUs, but the latest Linux AMDGPU shader compiler code update suggests that Arcturus is more of a professional GPU in-line with Radeon Instinct. It will most likely be manufactured on the 7 nm EUV node from TSMC and could launch in early 2020.
https://www.notebookcheck.net/New-Linux-driver-leak-suggests-AMD-Arcturus-will-be-a-Vega-based-professional-GPU.427820.0.html