Haha was definitely short lived. Almost as short as Tony Hawk games.
I doubt its over but definitely not going to see Guitar Hero III or World Tour like sales out of them anymore. But hey they did it to themselves. Can't release the same game over and over again with little to no changes and do it 3-4 times within the year. It's obsessive and it saturates the property. Not even a Madden or FIFA game more than once a year. But when you don't change anything this is kinda what happens.
But I doubt EA or Activision will just let it fizzle out. They'll keep up with attempts to push out their plastic accessories and new ideas and maybe they'll strike gold again.