I still think that Squall's failure to protect Rinoa when Hallow Bastion was overtaken by the Heartless is what prompted him to change his name to "Leon". Now, with the letter, we have an indication that she might still be out there, and he can go rescue her, those two can be all lovey dovey and kick butt together, and we can finally call him Squall again. Ooh, I hope so.