Idk, I still feel like handhelds can only continue exist as long as cellphone companies allow them to. They wouldn't even need to bundle a controller with the phone, just use some of that ad money to create a series of ads that position the phone as a gaming console as well, showing off any potential controller add-on. But that's typically not their philosophy I guess...
I had thought this, but I actually think that cellphone manufacturers just can't truly replace dedicated handhelds. The problem cellphones have with doing that is threefold. First, it's pretty obvious that consumers don't want any sorts of buttons on their cellphone. It is a lesson that BlackBerry is painfully learning. Second, those who actually do want buttons would prefer a keyboard or a number pad as opposed to a game pad. Third, any game pad is going to obviously split the market and cannot be guaranteed to be on every system unlike the touchscreen. Every game on iTunes and Google Play have to be guaranteed to work with a touchscreen and that will limit the types of games available.
Basically, smartphones are the equivalent to PCs in the mobile realm, so their control scheme naturally drifts to the closest approximation to a mouse, which is the touchscreen.
