Stating the obvious; but 5 year old CPUs in desktops are still mostly still good enough. Some incoming patches are screwing up older dual core setups, but otherwise there's little reason to swap unless you are doing heavy computations and/or gaming.
Even then, my 5 year old i7-6700K has plenty enough power for the forseeable future. The motherboard/graphics setup is more likely to be a limiting factor before the CPU and RAM are. Even then, a 970GTX is still plenty good enough to play just about anything albeit not at 4K. Not that worries me, when DosBOX gets more use than DirectX.