Given the economies of scale, in my opinion I expect the following:
Is this for iPad 2 or what? Anyway let me be your judge:
1) A "retina display" quality IPS LCD touchscreen, with resolution as high as 1600x900.
No. First, the next iPad will simply not get that much an update. The screen is iPad's most praised feature, so they will simply not bother (but yes, I want higher res too!) Second, while the resolution is at least more realistic than the 4000x3000 folks wanting super-high PPI, you run into problems with upscaling all the current iPad apps. And that's why higher resolution seems highly unlikely: If you just bump up resolution slightly, apps won't scale and it will be a compatibily nightmare. If you double the resolution so scaling is easier, well, resolution is way too high for the current technology. The answer? It's a downer, but the resolution stays the same for quite a while.
2) More memory, probably 512 MB to 1 GB RAM and up to 128 GB flash memory.
You're moving a little too fast IMO. Yes, 1 GB RAM would be awesome. Will it happen? Doubt it. 512 seems very standard for the next iPad, then 1 GB for iPad 3. 128 GB flash is a possibility though. Personally I think Apple will just keep the current storing options. Remember, Apple is not forced to do much here. Competition is very thin, and iPad is selling well.
3) A much faster A4 CPU (possibly as high as 1.5 GHz clock speed) or a new dual-core derivative of the A4.
Higher clockspeed,
maybe. A new CPU or dual-core I very much doubt. What are you basing this on? The thing here is, you expect higher resolution, and yes, then the iPad should be faster. But like i explained this is extremely unlikely in the near future. So, the A4 processor is good enough for now too.
4) A much faster PowerVR GPU that can decode 720p video at full resolution.
I think updated GPU is more likely than a new CPU, but these things are on the same chip right? I know little about this stuff, but I don't exept hardware changes either way. If 720p video can be implemented with software coding, sure.
5) Cellular-enabled versions to offer your choice of GSM (AT&T and cellphone carriers overseas that use GSM) or CDMA/LTE (Verizon/Sprint) support.
No. Making iPad a phone will be bad marketing, seriously. Really don't see this happening, and at this point I think you're wishing more than you'e expecting.
6) Will add the same cameras found on the 4G iPod touch.
Yes. This is the only thing on your list that actually seems likely, along with 512 MB RAM. Not sure about back-camera for video, however. I think it will just be a front-facing camera.
You wrote nothing about pysical changes in build. Personally, I think the possibility of slightly alterned looks of the iPad - perhaps thinner, possibly less bezel, somewhat lighter etc - is much bigger than new CPU and high-res display.
I'm guessing Facetime camera + 512 MB RAM +
maybe lighter/thinner device or a modest design change. Nothing else.