I use Linux as my daily driver, and I would agree that unlike the late 90's, it's a fully viable option, for sure. Absolute default for everyone, though? Doesn't seem like it. Not sure if that's what you were saying or not, but Windows is definitely still the frontrunner by pure usage.
Windows: 47.5%
Mac OS: 26.8%
Linux-based: 25.6%
BSD: 0.1%