I'm like AdamK47 and mostly use my desktop for games and movies/music, and do all work on a Surface Pro laptop. It's much slower than the desktop but easily fast enough for web browsing, office work and even software development. Beyond a point, the portability is far more useful than extra speed. Even phones are powerful enough these days, and I see teenagers often use only phones for everything. As said earlier, games and content creation are the only reason to use desktops anymore, and most people I know who aren't into either of those things have gotten rid of their desktops.
At work, I have usually had laptops with desktop displays and mice/keyboards for the last 10 years. One company used SFF desktops only for security reasons, as they didn't want anything to be remotely accessible.
That being said, I would always keep a desktop around at home (with a TV as a monitor). My desktop has 30 years of games, apps, emulators and Windows customization I've built up over the years. I've migrated them across many builds over the years, and it's become like a personal project at this point. I just did an upgrade of most of my hardware.