If current trends are any indication, the only way I can foresee the number of software engineers decreasing is if we make the job so complicated that the IQ floor on being able to perform at an acceptable level rises too high. We are currently piling the abstractions higher and higher, and we're patching them up with duct tape fast enough to keep most of the leaks at bay, but when things go south into Here-Be-Dragons territory, there are just a helluva lot more dragons lurking around these days, and they can be some nasty Lovecraftian dragons.