It would take something pretty spectacular for me to upgrade at this point. (After all, I've had my current iPad for less than a year..)
What are they going to put on a new model?
Camera(s): I can think of few things that appeal to me less than doing Facetime video calls. And I already have a great DSLR and a nifty Canon point n' shoot (plus a couple of 35mm film cameras, a pretty neat videocamera, etc.) Why would I want to do any creative photography with a device with a tiny lens, no zoom, no flash, and virtually no ISO or f-stop control?
Capacity: I don't generally use my iPad as a storage area for digital content. When you can buy a 2 terabyte hard drive for under $100 whats the point? My collection of digital movies, TV shows, and photos is kept on my home server. I can see possibly running into space issues if I'm not careful - but there's simply no reason for me to walk around with three seasons on Mad Men on my iPad.
More Memory/Faster Processor: I'm totally thrilled with my iPad's performance to date. It starts instantly, rarely gives me ANY technical issues, looks fantastic (ie. hasn't picked up any scratches, etc.) I suppose some elements of web browsing might be a little better. But there's no need to spend several hundred dollars just so I can hit the "back" button more often.
I generally plan on keeping Apple mobile devices about three to four years. Given the amount I use them, thats about the time the battery performance starts to drop off. And its also about the amount of time before whatever new models have come along have sufficient new features and/or performance that it makes sense to upgrade.
