Looks like the music game fad is all but over now: Activision shut down Red Octane and proceeded to major layoffs at Neversoft. I personally don't care about there ever being more and more gameplay improvements, as long as I can play songs I like, but at the same time I can see why some people would tire of the formula and of other issues (such as lack of interconsole compatibility or of backwards-compatibility of DLC with previous editions of the same game series).
And yet, to me, Red Octane will always be that third-party vendor of DDR mats for home use. At least Harmonix is still around...
http://www.gamespot.com/6298334