I believe he's saying that gaming on Linux today goes far beyond Wine, given numerous high profile games have been ported to Linux recently (in a large part thanks to Unity and Valve's Steam OS push).
Not really far if you count games that sell 1 million+ copies. Right now I'm playing Titanfall 2, Battlefield 1, Forza Horizon 3 and Resident Evil 7. And Hearthstone. Haven't seen a game that I would enjoy released on linux in ages. Even new Doom didn't get a Linux release, id software gave up.
I get the impression they never had much interest in Linux ports in the first place, it was mostly just Carmack's interest in the platform that drove it. But now his attention is elsewhere, so they don't have to bother any more.
I believe they skipped Linux because Doom uses some Windows-specific DRM. Even the demo is protected by DRM, and it won't work under wine for that reason. So they lost my purchase.
