Alright, pure theory, the existing updater can handle the swap. The whole 1.0 package has 5... yes '5' executable files. A boot engine, the actual game engine, log in application, the game configurator and the updater. All the updater does is check for a newer version and then download the needed torrent files. Then it will use the torrent engine to haul in the new installer/updater and files and launch that.

I think SE will surely announce alternative ways to download/upgrade. Maybe even an ISO on the SE accounts page if you are registered as a legacy player or in possession of a 1.0 key.