The Rift expansion will raise the level cap and add two new continents with solo quest content and a story quest arc. However, Hartsman suggested that it would be more fun to do the other activities that focus more on exploration. One example he gave was a quest alternative called "carnage" that does not require the intervention of a questgiver to get credit for killing mobs - a feature of Guild Wars 2 (and, as Tobold points out, something that Warhammer Online notoriously promised but largely failed to deliver). Hartsman states that players will likely get the exp they need from completing one of the two continents, plus all of the side exploration and carnage bonuses and other activities.
It's possible that Trion agrees with my speculation that GW2 may be a threat to their game due to some similar mechanics, and began planning a response well in advance of the competitor's launch. If so, one potential downfall might be all of the currently existing content in the game. Based on the interview it sounded like both continents were for the level 50+ crowd (though I'm not sure if this has been explicitly confirmed). Trion's answer to GW2 cannot be gated behind 50 levels of old content if they want it to be effective.