If there is to be a minor refresh to the iPad, it is no doubt being driven by the desire to have the new dock port on all of their iDevices simultaneously. It seems extremely doubtful that Apple would do this as some kind of strategy in maintaining sales against Android & Win8 products, which IMO don't represent a threat and likely won't until sometime 2013 (if that).
As I've said before, if Apple is motivated enough to change the dock port on the iPad 3, which will require an updated back shell, then why not make a few minor tweaks under the hood to address "perceived" issues like: surface heat temps, poor audio while filming, lengthly battery charge times. The first and last can likely be corrected by switching to a 32nm processor (same a5x though), which will generate less heat and allow for a battery shrink for the same runtime.
Ets Funn Spekulatin'