Is the Airbus A380 a viable shorthaul airliner?
I can't say if anyone has looked at a short-haul version of the A380, but we can look to the Boeing 747-400D for comparison.  

In addition to removing the wingtip extensions and winglets as described in the Wikipedia article, a friend at Boeing described to me other changes needed. Boeing beefed up the wing box due to the increased landing cycles. There were also some changes to the brakes to improve cooling as the short flights didn't provide adequate time to cool the brakes passively.  

It should be noted that ANA was the only customer with 19 aircraft built. They retired the last of them 3 years ago. So it would appear that there isn't much of a market for a short haul jumbo.