Ask HN: is Facebook's "GMail Killer" Going to Succeed?

So Facebook is planning to unveil their "GMail Killer" on Monday? Does anyone think they're going to be successful in their stated goal of killing GMail? More realistically, how do you see this product turning out? I think it could be a great product if they do it right and aim it to be the e-mail client of choice for the tens of millions of their users who predominantly use Facebook when they're online. If it keeps them on Facebook even more than they already are, then I think it has to be considered a success. No doubt Facebook plans to serve ads with it and integrate it with their existing products. On the other hand...am I the only one concerned that Facebook could potentially screw this up? Would it surprise anyone if they launched the product on Monday and then 'accidentally' let your installed applications also retrieve your entire list of e-mails? Do they get rid of the whole "Delete" button entirely?