2048x1536 resolution has a name: 2K (from the digital film world). iPads are already widely used on movie sets; this would more than cement that trend. Hope it's true!!!
I'm going to go with "unlikely".
I figure the high cost of 30" panels is due to the defect rate, which increases with number of pixels (which is why 1920x1200 displays cost about the same, regardless of whether they are 27" or 24"; same defect rate). And, I'd think it's easier to make a big working pixel that a small working pixel.
In conclusion, I highly doubt that the next iPad is going to have a screen of this resolution.