Yes. Mostly because your competitors (all of them) are releasing devices based upon the Cortex-A9. Never mind the fact that having a secondary processor to handle other tasks will let both sleep sooner.

If Nokia's high-end device of 2011 came out with a CPU others had used throughout 2010 and moved on from, they would be bashed so heavily in the media everything we hear today would pale in comparison, even if it worked as slick as could be.

That's not to say there won't be Cortex-A8 devices on the market, but they absolutely won't be the high end flagship device that they used to be. Motorola Atrix, LG Optimus 2X, Samsung's Orion based device, whatever HTC plans on releasing. That's the high end, and where the vendors will get attention.

Sure I can, so long as the OS isn't deliberately crippled. At best Apple could get away without it due to their furious marketing engine, however I suspect that the Apple A5 will match the rumors and be using a Cortex-A9.