Digital sales have already surpassed physical sales in the U.K. Don't forget that a huge portion of the game market comprises casual mobile games.
I'm not going to claim authority on the subject, but as a 100% real gurl gamer with real gamer friends living in the UK, I know literally nobody who still goes to game stores to buy their PC games. There is no point or reason to it. That's why game stores are either closing or shifting their focus to console games. It says nothing about the state of PC gaming - we simply have better platforms to do our buying through.
Also, I have an xbox360 controller, which I use for a couple of games, mostly platformers. I don't actually see much of an advantage to it most of the time, I just pick whatever feels good at the time - which, in my case, is usually the keyboard.
Parsifal, from what I've heard, setting up an x360 controller with Linux and Steam is easy. They're also pretty cheap, so you may want to consider trying that.