Most think that Photshop+LR are the sine qua non software for professional work, but that relies on a traditional view of low dynamic range photography. As mentioned in a previous post, HDR in Photoshop is not that great. HDR, contrary to the traditional view is not out of the main stream. One can argue that Ansel Adams Zone System is an attempt to map the dynamic range of the scene to the rage offered by the output device, in Adam's case, a particular paper and developer type.
Already, we see an increase in dynamic range with cameras like the Nikon D800. I am not an insider but I think it likely that there is a lot of research going on in this area. We may see much bigger jumps in DR in the near future. This would mean that HDR photography will more often be a one shot capture, not the multiples required now. In that case Photoshop will be at a serious disadvantage because its floating point capabilities are nowhere near optimum. Its historical evolution suggests that a fully floating point Photoshop product would be a big slog, requiring backward compatibility. I am thinking that will open the door to competitors. Kodak fell, Digital Equipment, Sun, too. The floor is littered with companies who once seemed invincible. And it does not take long when the ground begins to shift. Who knows? But it is not a certainty that Adobe will have a long reign.