If you can get such a controller for less than 50$ and already have a smartphone or iPod touch like device, then I just don't see why you'd want to buy yet another gaming device.
Now give me a good and comfortable controller for my iPad and I won't buy any console anymore.
Home console gaming currently offers gaming experiences that cannot be done on mobile devices. Mobile devices are only a threat to mobile consoles.
Remember Nintendo's investors threatened the board and wanted them to release Nintendo IP on Mobile appstores .
However it's good to note that GTA, Call of Duty, and Madden are all on the tablets and phones now. The publishers can't ignore the large casual gaming market.