The most-used operating system in the world has a Linux kernel. But, it might not be in front of you...except when you're checking email, waiting in line, playing Angry Birds, making a photograph, or checking up on Facebook.
I'm not a fatalist, I'm just pointing out a fact. FOSS is far from winning.
FOSS has barely "won" the lower levels of the stack and the highly technical niches. But the more you move towards user-facing applications, the more proprietary things become.