Oh it'll fly alright. And it will be very successful on a select few long range routes where landing slots are at a premium and current flights are almost always full. Many Asia-U.S. routes come into play.
The A380 may be most successful, however, as a freighter.
Which is why FedEx and UPS ordered the A380F.
Only for low density and palletized freight. The second main deck floor has weight limits. There will be no front cargo door for oversized cargo. It may be useful for Fedex and UPS, but it won't be useful for high value oversized loads.