The trends definitely favor a mobile-first approach going forward, if simply because of the additional systems integration work that goes into tuning laptops. Battery life aside, the laws of physics dictate that you're more likely to have a reliable experience with a low-power, low-heat, low-vibration machine than a screamer desktop, and those things are definitely qualities that the manufactuers optimize for in mobile devices.

It's also increasingly common to see single-board SFF desktops that are essentially laptop parts with different I/O. I suspect that those are less heavily tuned, though.