I won't try to predict when, if ever, they might do so, but I do think it's entirely possible they will if the market becomes big enough. There's been some sentiment here that Bitcoin is a direct competitor of Paypal, but I don't think that's really the case. Paypal is in the business of making it easier for people to send money to other people. Bitcoin does that too, to an extent, but as we've seen, keeping your wallet secure is a big task for many users, and if PayPal were to offer an Bitcoin wallet service, they could get a lot of users for that. Whether people would be willing to pay enough for the service for them to want to consider it is a different matter, but really I think PayPal would be just like any other on-line wallet service, only huge.