I think Linux already dominates/is about to dominate the markets it shines in (smartphones, servers, science sector/research, "thin" devices like Chromebooks). I don't think it will ever be a mainstream user OS unless you consider macOS linux-like. In my day job I work with physicists and grad students from top public and private universities and I've seen precisely 0 of them ever using anything other than Linux or macOS. My guess is mainstream users will gradually move to cloud-based platforms where the OS isn't doing much more than being a thin-client anyways.
Completely agree. The "desktops" days are numbered really... and the number of people using Laptops / Tablets / Phones not always connected drops everyday. If you are always connected chromeos does the job better then a "full" os like Linux,Mac, or windows. The masses simply don't need much other then a browser anymore. Even the old stand bye consumer software sales like Tax return software is going cloud based.
If Google doesn't try and go after the PC gaming market... they may win gaming it in the end with little change anyway. As game streaming becomes a realistic mainstream option in 5-10 years "android" type boxes, and netflix like gaming apps will become the norm for gaming.