I'd describe the mobile hardware as comparable to computers from about eight to ten years ago. It's a rough ballpark and a very imperfect analogy, but basically the things we were doing in graphics circa 2005 work great on the mobile chips now. That's around the timeframe of the Xbox 360 release and puts games like Half Life 2 within reach, so it's not a trivial amount of processing power by any means. I think it's reasonable to assume a similar trajectory of evolution, with the caveat that mobile is already running fully unified shader GPUs and so they're actually doing a little better than PC hardware in that sense.
That would be for latest and greatest tablets (which capabilities might be available to 'average' smartphones half a decade on)
Also thats Half Life 2 'running', but lower-end settings (Return to Wolfenstein at high/decent frame rate might be more expected example?? - which is actually alot gamewise)
And with the high utilization (all cores/GPUs going ) burn rate, will batteries last long enough (though the 'on the go' use-case Im thinking of would be 15-60 minutes) . The target would be ordinary devices without significant extra inconveniences require to enable casual use.
Nazi Zombie mode CoD .... hmmm
I realize that mini-games usually are limited as secondary (when companies have enough trouble developing/sustaining the primary game) but this fits in with (future) new generation games with a massive player created asset component (thats why I push it out 5-10+ years) where there will be alot most 'stuff' to peruse and peoples gaming time will probably be broken up even more than today (hence a need for more/integrated 'mobile' use).
I was justt considering some more and we might need 5-10 years to get some of the ergonomic issues (display and input) -- a seperate issue....
I dont know about you but Im getting older and holding one of those tiny things infront of my face to see sufficently (and for a duration) a decent FPS game AND work game controls a bit more complex than fingerpainting on the screen --- they will have up with some clever stuff to push that kind of useability forward.