Let's get the Apple angle out of the way. By now, the iPad 2, which from what I've been able to find out, is still in high demand. And given that it's already more than 2.5 years old, Apple is making a hefty margin on it and adding to its growing pile of cash.
So, why are people still buying it? It's $399. And probably lower if they're bought on lots of hundreds or thousands. Businesses and schools come to mind. Tim Cook unveiled yesterday that Apple has an unprecedented 94% of the tablet share in education. And schools are looking at the full sized iPad to give their students. I'm willing to get a large number of those are iPad 2 tablets. The only competition I see the iPad 2 has in the near future is from the iPad mini coming in at $299, which is essentially the iPad 2 with a 7.9" screen and a better camera.
Also, businesses are still buying iPad 2 for their workforce. It's light, performs decently still, and, again, cheap. If you want to use it as a transaction register (I didn't call it a cash register because the iPad 2 just doesn't take cash) along with a device like Square, it's cheaper than buying a big bulky and expensive cash register. I've seen more and more businesses turn to iPad use in the manner. There is no need to get a more powerful and expensive iPad 4 to do this simple task of swiping a credit card and taking money from it.
And on top of that, the iPad 2 does run iOS 7 which comes with it more features and better security which is a plus for enterprise,small biz, and schools (assuming Apple can find a way to keep resourceful elementary kids from hacking its lockdown system).
Want an example? Check this out. Southwest will be deploying the iPad 2 as an entertainment solution on its flights to let flyers watch shows on the Dish network. How awesome is that? (9to5mac). And how many thousands do you think the airline have bought from Apple? And also, Dish is giving out a free iPad 2 if you sign up with it and get a Hopper too. (Dish)
The question is what happens next year? Conceivably, Apple could make iOS 8 work on the iPad 2 and iPad mini with further limitations but it is also moving further down the road on the 64-bit roadmap. We'll have to see how Apple deals with the $399 sweet spot that the iPad 2 as well as the $299 iPad mini sits on now. But that's speculation for another day.