Anything that you need to run on a desktop can't be used effectively on a touch screen anyway, so phones and tablets don't really count for serious software. (Writing this comment is stretching the bounds of what I can reasonably do on an IPhone).
In many ways, the consumer and non specialty business are post desktop. Turns out documents, email, and other communication apps cover 90% of use cases. Anything that requires major performance gets rendered in a cloud and delivered by these other apps.
https://gs.statcounter.com/os-market-share/desktop/worldwide
I'm finally upgrading from an Intel Sandy Bridge processor after nine years, and I still don't need to - it's cranking along pretty well as a dev and gaming machine still.
https://www.statista.com/statistics/272595/global-shipments-...
Note that this data is missing phones.
2010: 157mm Desktops, 201mm Laptops sold 2019 forecast; 88.4 + 166mm
Or, perhaps better, is in terms of internet use https://www.broadbandsearch.net/blog/mobile-desktop-internet...
Mobile went from 16.2% to 53% of traffic since 2013; nearly 4 fold. Which means since 2013, non mobile usage went from 84% to 47%; or nearly 50%
But there are definitely examples within Accountants, Animators, and Musicians where Phones, Tablets, and Chromebooks (not specialty desktop apps) have taken over the essential day to days.
For animators; the Ipad VS. Surface face off is a great example -- also where they offload concepts to "the cloud" to render instead of a Mac Pro.