Harry Marks over on Curious Rat nails it on people complaining about the third-generation iPad’s relatively early demise:
I still see people using gen 1 iPads daily and a lot are still on the iPad 2. So few people upgrade every year, especially with something that can be constituted as a PC replacement for many of them. I think the first iPad was a rare miss for Apple in terms of built-in obsolescence. I don’t see it making that same mistake again. The iPad 3 has enough CPU power and RAM to keep it going for quite awhile.
But even so, this is progress. This isn’t a new Motorola Droid three weeks after the last one came out. This is a new iPad roughly 7 months after the last one and as big as a CPU bump as Apple makes it out to be, it does not null and void the existing third generation iPad.
I own a third-generation iPad was surprised at this announcement, but am not angry or feel betrayed like some of the pundits Marks quotes. I think the ideal scenario would have been to hold off on releasing the third-generation model until an A6-based model was ready, but the iPad 2 was getting a bit long in the tooth. As the iPad 2 is still being sold and the iPad mini also features an A5 chip, I doubt the third-generation iPad is going to be abandoned anytime soon.