The only camera bodies I have, that I bought new, are a Canon 7D, and a Nikon Coolpix A. I bought my 7D in 2010, and liked it enough that I bought a second, pre-owned 7D, to have matching bodies to use at work. These 2009-era cameras are working quite well; I feel no need to upgrade, as my employer does not have a need for large prints. (evidentiary photography, at night) Some newer Canon models may do better in low light, but I use powerful Canon Speedlites that negate any advantage a newer body may offer.
I could just as well have kept using my 40D for evidentiary shooting, but the 7D represented a significant step forward for Canon in Auto White Balance, which is very useful in mixed lighting conditions, so I do not regret the upgrade. In daylight, or when I can control the lighting, the 40D is still an excellent camera, and I plan to keep mine forever.
The Nikon A was released last year, but it being a fixed-lens compact, is not a replacement for a DSLR.
My wife feels no need to upgrade her camera. She shoots forensic/evidentary images with a Nikon D7000, which has been superseded by the D7100.
I have already started using "full-frame" DSLR cameras, for personal shooting, but I acquired them in pre-owned condition, at considerably less than half their original retail prices, after successors had been introduced. Of course, my D700 can be considered quite an upgrade to the Canon 7D, despite being an earlier-introduced model, but the point is that one need not have the latest, newest camera, nor is there a need to upgrade with each generation.
Canon 7D/5D/40D/1D2N; Nikon F6, D700, FM3A, & Coolpix A; Canon 40mm 2.8 STM, 135L, 50L, 35L, 50mm 1.8 I, 100mm 2.8L Macro, 10-22mm EF-S, 28-135 EF, 400mm 5.6L; Nikkor 50mm 1.2 AI-S, 50mm 1.4G, 50mm 1.8D, 16mm 2.8D Fisheye, 180mm 2.8D, 100-300mm 5.6 AI-S, 18mm 2.8D, Voigtlander 90mm f/3.5 SL II