I suspect that you'll be able continue to use the tried-and-true methods, far, far into the future. OpenGL and DirectX11 aren't going anywhere anytime soon, and there are still games coming out with DX9 minimum specs. Last time I checked you can even use mid-90s OpenGL immediate mode calls.
At the very least, there will continue to be support for all of the thousands and thousands of legacy games, one way or another.
At the very least, there will continue to be support for all of the thousands and thousands of legacy games, one way or another.