Bungie has not said anything about this yet so the only correct answer is "We don't know." That said, speculation time: Your character data is stored on Bungie's servers so the info is there to be referenced as needed. It might be possible that when you start D2PC for the first time it pops up a launcher asking you to log in to your Bungie.net account. From there is could read your account data and show you what characters, if any, are available for import to PC, as well as giving you the option to Not import any characters and start over. That's how I would do it anyway, but I'm not savvy as to the legal exclusiveness any whatnot.