Gaming has moved from the desktop to the laptop or game console.
That comment has been made before... many times...
You know what? The irony is that a PS4 or XBox One is really a desktop PC, abit one that you can't modify or upgrade much.
Yes, much of what the average person does with a computer works fine on a tablet or laptop, nothing wrong with that. The one area that will have problems for a long time to come is games.
And by games, I don't mean solitaire or candy crush, I mean Call of Duty type games. Those need lots and lots of power, something you can't get in a laptop due to size/power limits (there are rare expensive exceptions, but a desktop is still the best choice for those.
Yes, game consoles play many modern games as well, but they have the benefit of fixed hardware that can be optimized in a way that PC gaming cannot be, but that is also their limit.
The PS3/XB360 were great at launch, but REALLY out of date by the later years. The PS4/XB1 are fine today, but already they are behind a decent PC's performance.
4k gaming will require a whole pile of GPU resources the current machines do not have and it may be 7+ years before we see PS5/XB2.
The PC desktop market will never again be what it was in the 90s, but it isn't going away either.