Don't worry, by that time you should have Valve's Steam store and a good portion of its vast library of games
ported to Linux. It's till in beta but so far Valve's ports of its own gamers and engine are already
faster in Linux than in Windows!
The back story for this is interesting, and it is related to the changes in business model that Microsoft has made with Windows 8. Microsoft has been trying to copy Apple's rent-seeking strategy by setting up an "app store" for Windows 8, but other distributors selling software online for the Windows platform were quick to smell the rat: every time Microsoft tries to get into a market leveraging their Windows system they go for monopoly, wiping out any former "partners" who are in the way. Thus Valve is moving to find a good alternative to Windows. An open alternative where an owner of the platform can't sabotage their business. Linux is the obvious choice: it has so far been used industrially for everything from kitchen appliances to TV sets, cars, mobile phones, and supercomputers precisely
because no one "owns" it, no one is in a position to screw users or developers.
The only thing linux lacked for gaming were companies with clout developing for it. That's a done deal now.