I'd love to see Apple get out of the carrier-specific business, and develop a single cross-carrier iPad. Not only would this stimulate pricing competition among carriers, but it would make purchasing an iPad that much simpler. For instance, my parents want an iPad but I don't know whether to advise them Verizon or AT&T in their part of the country. So many choices, some better than others, goes against the usual "just works" philosophy.
Also, technically, it's entirely "feasible" to make a world iPad -- just recently we saw this, remember?
https://www.macrumors.com/2011/02/07/verizon-iphone-carries-world-mode-gobi-chip-from-qualcomm/
Even if the iPad were slightly heavier and thicker due to redundant antennae, I think it would be worth it. I don't like tying my iPad purchase to the long term fortunes and pricing whims of a single 3rd party mobile phone company.