I doubt I'm going to buy a new iPad until someone pays me an extra $10K per year, but here's stuff that sounds doable and intriguing.
1) Fingerprint recognition. If iPhones support this, iPad support is a big duh. I see plenty of people carrying around iPads to use as cameras. This is the only device some people have, so it makes sense. It really makes sense if it works for security (new unlock method) and purchases (more secure than any password).
2) Thinner, lighter, faster. It's Apple. Duh. The obvious move is more toward the reduced bulk of the iPad mini. But is it possible with a Retina display?
3) Battery life. I know the MacBook Air benefits from new Intel CPUs. But if there's A-series tech that gives anywhere near that kind of a boost, boo yah. I have no real complaints about my iPad's battery other than how long it takes to recharge and my cheapo PC notebook not charging it over USB.
4) Cheaper cellular. I would think about buying a cellular version if the price got down below $100. I'd like to have the option for something I plan on owning for a few years, and that means you get built-in GPS.
5) Mo storage for cheaper. Get rid of the 16GB option in the full-size iPad. Unless you do nothing but go through websites and use email, you need more. If you get into Newsstand or buy media (music, videos, etc.), you're going to need more storage. Just turning on PhotoStream takes a huge chunk of that. If PhotoStream ever were to include videos you shot, holy moly. Leave 16GB to the mini. (And while we're at it, get rid of the darn iPad 2 already).
6) Better speakers. I cannot play most stuff tilted one way because I am used to the sound coming out the right side. So figure out a way to get better speakers.
7) Better cameras. I never use my iPad as a camera. Is this why iPads don't have better cameras, or would I use it more if it had iPhone 5-quality cameras?
8) A USB port and SD card reader. I'm so kidding. I'd rather see other manufacturers figure out that we have 18,000 different wireless technologies. Why must I still take an SD card out of a $200 camera and download pictures? Unless I spend $50 on a card that normally costs $10 or buy one of those Android-based cameras at $300, that's the deal. (Apple, make a smart camera. Please.)
9) Streaming media. If I can stream movies, music and TV shows on my Apple TV, why can't I do that on my iPad at least over WiFi? Oh, and figure out a way to get iTunes Extras on there.
10) I've run out of ideas but I like even lists. You guys suggest something. Wireless charging? 16x9 aspect ratio?