My monitors rarely last that long (at least, before I find it's worth it to upgrade), but like a lot of folks, I put most of my money into good monitors, keyboards, and color laser printers rather than the computers themselves, because I can generally get at least 5-10 years out of the peripherals. Computers themselves rarely last me more than 3-4 years, although my wife still uses one of my old Surface Pro 3s as her main computer - it's held up better than the SP4s.
If I could get a pair of Surface Studio touch monitors to dock with a Surface Pro/Book, I'd buy them, but yeah, I'd be real careful with them, too...