People will play because of the Elder Scrolls setting. A majority of people will probably last 3-5 months in the game, due to the lore, questing, and end game PVP content. It'll be a bit more popular than Guild Wars 2, I think. Perhaps a bit less, considering the payment model they've chosen.
More popular than GW2? Never. At least not in its current p2p model (i think its p2p)