In terms of plateuing, they got a bit stuck on cpu speed. When that started to happen, the manufacturers started adding cores, essentially making PCs multi processor computers. They now have many. To begin with, Windows wasn't good with multiple cores, and applications didn't make use of the additional cores very well. Solid state drives made a big difference. Now things have slowed again.
The next really big thing is going to be moving away from 2 state digital. In 2 state digital, the two states are often referred to as 'on & off' or '0 & 1'. There are two voltages, one for each of these states. In 2 state digital, there is actually a third state. That's no voltage at all. No voltage is an error state. It's been this way since the early days of electronic computing. That's all about to change, and it's going to be huge. It will allow very powerful computers to also be very small.
I once put Linux on a work computer, in an office. It didn't go down all that well. Linux is great for some stuff. Windows is good for running software that you can't get for Linux. Windows is good for games. Linux was good for not getting malware. That's something that has improved with Windows of late. Linux is great if your computer is old and slow, if you want to run a server, and there's no messing around with licenses. The audio players in Linux are all a bit naff imo. I flit between Linux Mint and whatever is the latest Windows. Over the years, there's tended to be at least one thing that won't work for me, at all, on Linux, which makes me return to Windows. Though I do have a soft spot for Linux.