I would also like to point out that since I'm in the PC build/repair business, desktops are most assuredly still very popular among gamers and non-gamers, and PC gaming popularity is steadily rising due to being more cost effective in the long term.
I assume that your not working for dell etc, It's the big numbers that really count.
PC building market is more specialised than the bigger brands, besides everywere were you look desktops have declined in sales over the last 5 years. Obviously some companies could see a rise in their profits thanks to being in a certain part of the market
Gaming is only a part of the pc world, in the past many people used desktops for saving pictures checking mail or searching the web only.
I hate bringing out the stereotype but I'm pretty sure that (especially thus meaning not all) gamers have or will buy a new desktop or people who really need one for work offices etc. For those groups desktops will remain popular for a very long time.
However a very large part does not need a desktop for the more simple things anymore old or new. It's pretty easy to see why desktop sales have declined over the last 5 more or less years. Not to mention that laptop sales have dominated PC already for a very long time.
Even in the early years when the laptop was being brought just into the market. It's more mobile and thanks to that being more popular than the static desktop
http://www.businessinsider.com/pc-sales-decline-year-chart-2017-1?international=true&r=US&IR=TDon't forget that these sales include laptops in a dominating fashion wich already lack allot of power it is also said that laptop sales have improved within these figures while desktop sales have dropped more and more.
However even laptops are being replaced by tablets and not covering the losses of the desktop sales and thus still declining in overall sales for personal computers.
https://phys.org/news/2017-01-personal-sales-fall-year-row.html