Unless it's changed or I'm mistaken ( both are highly possible
) Star Citizen uses no P2P technology apart from their launcher when it downloads files.
I read an article by Chris Roberts (
LINK ) where he explains how instancing works in SC. They have a Galaxy Server, which hosts every single player in the game, and because it doesn't do any rendering ( only transmits data information and telemetry ) it can hold hundreds of thousands of players. When an event occurs (e.g.: leaving a planet) the player is placed into an instance ( either existing or newly created ) on a sort of "combat server" by the Galaxy Server.
For the scope and scale of Star Citizen, I don't see them moving to a P2P setup.
I'm speaking under correction, of course.