This makes little sense to me because we're reaching the point of diminishing returns when it comes to mobile computing performance.
I just bought an HTC Thunderbolt for the 4G/LTE access, and it's a single core that does fine. Ditto with the Droid Charge.
Imho, a fast single core is enough for web-surfing and watching HD video and play Angry Birds and such. But I suppose a small pool of people will attempt to play demanding video games on tiny little screens. But dual core and lots more video performance doesn't seem necessary right now... maybe a little more performance to encode 1080p video or something, but beyond that, it's overkill. Dual-core with high-performance video seems like unnecessary expense and energy usage at this point. Quad core seems like an even bigger waste of energy.
Energy efficiency is a big reason why ARM beats INTC in the mobile computing space and why INTC is making such a fuss about its energy-efficient 22nm process... they NEED to be much more energy-efficient if they hope for x86 to trickle down to mobile computing devices.
Give me adequate performance at a lower price with better battery life any day. I don't need to or want to play BF3 on my smartphone, thank you very much, especially if it adds expense and lowers battery life.
Edit: For tablets I see perhaps a bit more need for performance, but even then, beyond stuff like encoding/decoding 1080p video, then what? Does anyone seriously think we will see hordes of hardcore games being developed for tablets (especially given Nintendo/Sony probably not wanting to open up their hand-held console businesses and Sony probably not wanting to cannibalize its PSP business)? Does anyone even WANT to play demanding games on tablets and sub-10-inch-screens? There's a big difference between casual games like Angry Birds and demanding games like Crysis 1. You'd need a keyboard and mouse to really use a tablet for hardcore gaming, at which point you might as well get a full-fledged x86 laptop instead. Or just go desktop or console (Xbox 360 w/ Kinect, PS3, Nintendo Wii). That's not to say that ARM might not dominate lower-end mobile computers (netbooks, tablets, smartphones), but I have a hard time seeing ARM compete with INTC/AMD in the full-fledged laptop space.
What you would do and what the market will do are not the same. Hand held gaming devices are going to be replaced by phones and tablets. That is the bottom line and why there is a road map for ultra mobile devices that include 4 cores and beyond. Once upon a time MP3 players were a popular stand alone device. Now they are integrated onto the phone. Once upon a time digital camera's were stand alone. Now they are on the phone. The goal is to make a phone\tablet the end all device for people to use. From multimedia to gaming, to productivity.
Most people are not "hard core" gamers. Most people can get by with Intel integrated graphics on the desktop\laptop.
ARM doesnt need to compete in the desktop\laptop space. The market will continue to move towards tablets and smartphones.