Once again, the repulsive spectre of the iPhone rears its head. While mobile gaming has come on in leaps and bounds over the past few years, due to advances in hardware and screen resolution, I really don't see mobile phones obsoleting the 3DS and Vita anytime soon. Three reasons spring to mind:
1) The Apple "lockdown" thing. Many gaming titles are cross platform, even when it comes to mobile gaming. The latest garbage movie tie-in always spreads itself across as many system as possible, like a fat man on a sofa. It's to see the studios agreeing to have their gaming cash cow purely on one system only.
2) iStore, Amazon, et al: Developers tend to make precious little from sales as it is without Apple or Amazon's App Stores taking a hefty chunk of the proceedings from any title sale.
3) The big one: Controls. Controls. Controls. Ever wondered why the majority of titles for mobile phones tend to be quirky games such as puzzlers, casual games and strategy? Its for the simple reason that touchscreens are awful for anything fast paced. Can you imagine trying to play something like Street Fighter 4 using only a touch screen? Or perhaps a snowboarding game where you have to enter a hundred and one different button presses to pull off that amazing combo in mid air? Even if it were possible to enter commands that quickly and have everyone register exactly the way the gamer intends, you wouldn't be able to see half the action on the screen because your fingers are in the way!
Example: I bought a game called Sky Force on my Android phone. It's one of those vertical scrolling shooters that were in vogue back in the 80s, when I were a nipper. The graphics and sound are fantastic, the power system is good, bla bla bla, but I always end up getting stomped by things flying from the bottom right of the screen where my hand blocks the view.
More than that though, have you ever tried playing a game on a phone for a long period of time? Its a fantastic way to end up with your wrist and hand in agony for hours afterwards? Something with an involving storyline will have me playing for hours on end (say FF IV on the DS or Castlevania on the PSP). My hand would not physically be able to do that with a touchscreen on a phone due to the ergonomics involved.
So please, can we finally ram a stake through the ever recurring idea that mobile phones will be the death of the DS and PSP? Not in their current form they bloody won't.
PS: This argument applies equally to both Apple and Android fanbois, so you can both shut the hell up.