I considered this when the ipad3 came out...I was convinced we would see a 128GB model....We didn't. If the rumours surrounding the iMac being base 8GB RAM prove to be true, it would make sense for Apple to drop the 16GB ipads and start at 32GB.
That's not the case with the phone though....A lot of people use the iphone purely as a communication device, just taking the odd picture etc. 16GB is ample for that.
I've always bought top end when it comes to storage...And if the Ipad4 or whatever they call it has a 128GB option, I'm there. I can fill 64GB very easily...Probably because I'm lazy at data management...🙂