There's nothing in photoshop that is particularly "secret saucey". Any competitor could fairly easily implement any single Photoshop feature based on their own research and/or reading siggraph papers. The value of Photoshop is in the entire package and also in the easy integration of it into all of Adobe's other tools. A competitor getting access to the code couldn't really benefit from that in a way they could legally get away with (it would be really obvious if they just dropped massive chunks of the Adobe code into their own product).

While this is an unfortunate situation for Adobe, I doubt it changes anything for them in terms of Photoshop sales now or in the future.