When a new product is created, companies compete initially on features. When all the essential features are there (take radios, for example: most radios have the basic features down), innovation starts. Innovation, such as portable radios, radios in your car, etc. push the industry forwards for a while.

Eventually though, innovation stops (I don't see many new radio sets today). When that happens, the product becomes almost a commodity, and another product improves so greatly upon it that the other product can be considered a new product.

Television, for example, replaced radio (two senses versus one sense). The internet, arguably, appeals to the same senses, but allows for user-created content, more freedom, etc.

When we reach the upper bound of innovation for television sets, it too will become a commodity. Perhaps it will eventually be replaced with a product that not only exceeds the capabilities of human sound and sight (for television to hit the bound for innovation, this must happen), but also incorporates something else: maybe it's another sense, maybe it's something more convenient (I guess the internet, could, to some extent, be considered as an evolution of television).