I would like to chime in and express, in hopefully a less demanding but nonetheless passionate manner, my strong wish for a Linux version as well. A couple of days ago I purchased Affinity Designer for Windows but my primary OS nowadays is Linux - as it is for the majority of Visual Effects artists actually, since most VFX studios run on Linux. For most of us, Photoshop and ZBrush are the only reasons why we still have to dual-boot into Windows, and while there are valid alternatives for 3D sculpting on Linux (Maya, Blender, 3D Coat), Photoshop or Illustrator have no real match on Linux, unfortunately. I can speak for myself and many of my colleagues that we'd be more than thrilled to ditch Photoshop and Adobe if Affinity would allow us to use Designer and Photo on Linux - and I'd gladly buy another license for that. :)