A reader wrote me because he was worried about the effect of server age on the RvR combat of Warhammer Online. RvR in WAR is divided into 4 tiers, so that even the outcome of the RvR between the lowest level characters has some influence on which realm is winning. What happens if like in WoW everybody hits the level cap after a certain time and there are few or now low- to mid-level characters around? I told him not to worry. As far as I've seen in the video podcast the lower tiers contribute to the result of the higher tiers, but it isn't necessary to win the lower tiers to capture the enemy capital and win the war.
But the question assumes that the time to level cap in WAR isn't significantly different from the time to level cap in WoW. And that might be a bit too early to presume. Time to level cap is not the same for all games. With World of Warcraft having been such a huge success, there is a danger that other games copy as many features from WoW as possible, not knowing which one is the secret ingredient. But I don't think that WoW got their time to level cap exactly right, there is still room for optimization.
Early in World of Warcraft's history the PlayOn blog made a census and determined that the average player took 21 days, or 500 hours to level to 60. But their latest count has people leveling to 70 in 15 days, because of players now being more familiar with the game, there being more spoiler sites, and because of all the twinking going on. Wrath of the Lich King raises the level cap to 80, but makes leveling up through the mid-levels faster, so time to level 80 will probably stay below 500 hours.
500 hours or less to level cap is rather short. Everquest wasn't as meticulously studied by third parties as WoW is, but inofficial polls at the time of the Kunark expansion revealed an average of over 2,000 hours to level 60. Personally I never got to the level cap in EQ1, I got stuck at level 42, with some unfortunate deaths costing me so much xp that I didn't level up for weeks until I finally gave up. The problem with the time to level cap is that people tend to experience that time in real-world weeks, regardless of how many hours they play per week. If you'd play only 10 hours per weeks, even WoW would take you a year to reach the level cap, and Everquest would take 4 years, which is way too long. But if you play 40 hours per week, you finish WoW in 3 months, and Everquest in a year.
People like their characters to progress. Advancing too slowly along the leveling curve is bad, but hitting the level cap and not advancing any more except by gathering better gear and reputation is bad too. Some features of a MMORPG, like raids and the ultimate PvP, is only available at the level cap. The level cap is the big equalizer, where all the people playing at different speeds finally end up having the same level and thus being able to play with or against each other without level difference getting into the way. With time to level cap being so short in World of Warcraft, the level cap turned into "the place to be" far too quickly. Many people nowadays just rush through the game to get to level cap, some even paying powerleveling services to level their characters up for them. It is a game design which places the best content at the end which makes people want to skip the leveling part of the game. And I don't think that is the optimum way to do it.
Other games, for example City of Heroes / Villains, did a better job of overcoming the difficulties of level differences before the level cap, by giving players the option to adjust their level to that of their friends and play together with them. It is easy to imagine a game having more content in the low- and mid-levels, and not reserving all the epics for end game raiding and PvP. If there was simply not much interesting stuff to do at the level cap, people wouldn't be in such a rush to reach it. You could make games which took longer to reach the level cap, lets say 1,000 hours, and make all of that time more interesting.
Unfortunately EA Mythic thinks that by offering end game RvR they have found the miracle cure of MMORPG longevity. I'm afraid leveling up in WAR won't take any longer than leveling up in WoW, and after an initial phase of exploration many people will rush to the level cap as fast as they can. It might get even worse than WoW, because some people derive their self-worth out of being able to beat other players in PvP. That is a bit pathetic, but sadly it is part of human nature. And I am not sure that the first rush of kicking ass in realm wars will last very long. I might not be the biggest fan of raid content, but at least it is some sort of content. Relying on players to entertain each other in RvR without the developers contributing any content is probably not going to work for years and years. My hope for WAR is more on the PvE side, because apparently all 6 races have their own zones from level 1 to the level cap. So even if the end game turns out to be boring, WAR might have good replayability. There is always hope.