What percentage of the content is geared toward players of all levels, and what percentage to only level 60 (and above with the level cap increase) characters?

Shane Dabiri: As is traditional with MMO expansions, a large portion of the content will be geared toward characters in the range between the current maximum and new maximum levels, starting at around level 55. However, we do also plan to add content to better tie in the new races to the world, so players who choose to start as one of the new races will experience a great deal of new content up to about level 20.