No they won't and I haven't seen or played a free to play video game that's followed that model since I've started gaming online 6 years ago. Not even the crappy free Korean mmo I played followed that business model. Not saying games like that don't exist but they definitely seem to be in the minority when it comes to popular titles.
Arenaet is really pushing gw2 as an e-sports title they're not going to ruin competition through cash shop items. Just about everything at max level is going to be cosmetic whether it be from the cash shop or found in game.