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.
I hardly doubt some competitor will pop up with a bunch of cloned features from photoshop's codebase, and suddenly hurt their market position.
There's hardly even a single competitor to Photoshop in the first place.
There is unfortunatly no room for real competition. All the print/photo industry is locked in proprietary file formats (psd,pdf,...) all owned by Adobe. And piracy is actually hurting small shops, not Adobe.
As we move into the cloud there may be room for more focused Saas apps(like a web version of Lightroom or Fireworks), though i'm afraid Javascript/HTML5 will not deliver the required performances(unless JS becomes as fast as C).
> All the print/photo industry is locked in proprietary file formats (psd,pdf,...)
PDF is actually an ISO standard (32000-1:2008) and Adobe has granted a royalty free license to use all Adobe patents to implement the standard. They have also said that all future versions will be defined by the ISO committee.
PSD is proprietary but documented and implemented by a number of programs.