There is no point even considering the potential of Guild Wars 2 until it is released. Even when they eventually get to beta, beta is free. You don't have to buy the game to play the beta. While the game itself will be F2P, you must also take into account the number of people who buy it. In order for it to be profitable, it will have to continue to sell the game over an extended period of time not including providing Pay-to-Play services that will expand the game for players that already own it.
A F2P is a much more complex beast than a Sub-Based game simply because they have more to sell (F2P is a huge misnomer) and much less reason for people to buy what they offer.