There are plenty of people using those platforms, even game developers prefer to target stable hardware, than zoo configurations.
However what isn't happening is the growth that shareholders love so much, because like in other industries those MBA folks still haven't understood there isn't such thing as an infinite exponential growth curve.
As 70's child, before those MBAs even cared games industry existed, many of us had to contend with a single new game per year, or learn how to program our own games, now we are in a state like 1983 crash.
There are enough games to play even on lousiest platform, than most people have time on their lives to finish.