I'm calling it, Sora infiltrates the Keyblade Hunter's HQ and somehow access their mainframe computer.
He sees this particular list but random Keyblade Wielders that got exterminated in Quadratum.
Most are strangers, but you recognize them from the prequels.
The more people talk about Yozora the more I won't be surprised if the people in Quadratum used collected data from slain Keyblade Wielders to create other means to destroy the Heartless.