Well, yes, things have changed. The number of games available on Linux has increased by orders of magnitude, and the variety of those has become more diverse.
The post OP references seems to boil down to the eternal question "can I give up Windows and switch to Linux, but still be a hardcore gamer?"
Obviously the answer depends on how you define "hardcore gamer"; if that term means "someone who plays all the games that are released on the market" or "someone who plays only the top 5 most popular games on the market" then maybe not, since by these definitions, you'd have to guarantee access to all the new games (good or bad) or at least all the popular ones that the gaming media chooses to buzz about.
But if you define "hardcore gamer" as someone who spends days at a time playing through games they enjoy, then the answer is a resounding yes. Between Steam, GOG, and those occasional Kickstarter projects, there are plenty of quality games for Linux. Some a "triple-A" titles, others are mid-range, and still others are indie oddities. But most hardcore gamers enjoy the whole spectrum, so as long you don't have a hard list of "must have" games that you cannot like without, then quite probably you're going to find plenty of material to keep you gaming on Linux for days at a time.
This isn't unique to gaming, though. In the end, people who are comfortable with their OS are not going to switch to something less familiar and which involves trade-offs. It's the same reason I won't be switching to Windows from Slackware: I don't know it, I don't want to learn it, and I don't want to give up the power and freedom that Linux provides. Simple as that. If a gamer is annoyed with Microsoft enough to move to Linux and can live with the fact that no, they cannot have Dragon's Age: Origin on Linux natively (but could play Divitiy: Original Sin as a pretty great alternative, or else use WINE), then yes, they'll switch and they'll be happy. If the lack of some game is a dealbreaker, then they'll not switch.