PC isn't dead, PC HW market is slow, as once they buy a PC, most users are fine for a long time, but the existing user base is huge, and slowly growing too. PC power users is a much smaller niche, this is true, but games don't require those configs to run, otherwise they wouldn't run on consoles at all.
What could actually happen in PC market is a shift to cheaper Android machines for many home users, leaving x86 and Windows the leadership only in workplace PC's market (but many new companies without x86 and Windows legacy could switch to a cheaper platform too).