However, it will be interesting to see how long Apple can keep up with the same processor. 70% larger battery while still lacking Siri is indicating that Apple is has stretched the limits of existing processor technology. Apple may be lighting the fire but I see Intel enjoying the warmth in near future. -----
The larger battery is for the screen/GPU not the CPU (it'll draw the same as the Ipad 2). As for Siri, again, nothing to do with the CPU as the slower 4S can handle Siri fine.
As for how long Apple could go using the same processor (I assume you mean CPU), it could probably stay with this CPU for another product cycle (iphone 5/ipad4) but with a clock bump when it goes to Samsung's 32nm process (the clock jump could be significant without drawing more juice). Beyond the A9, you have the A15 and the A15/A7 hybrids so Intel's got a few years yet to wait before Apple come running.