Is the A350 not the Airbus answer to the 787 and the 747-8I Boeing's reply to the A380?
Yes, the A350 was designed to compete with both the 787 and the 777. Not sure if the 747-8 was designed as a direct competitor against the A380, but no doubt they'll be in competition for the longer routes.
Looking around the net, there's more than a few sites which have pages about trying to compare the 787 and the A380, even though those aircraft are so so different from each other. I guess the only way to compare them is how well they do in service.