I feel your pain, itsame, as I've had the same issue. It's pretty frustrating since this is the only game I've had any sort of IR issues with of this duration. I've been running screenwash programs regularly to some mild success, but the IR is not fully gone yet. I'm also running a 2012 Pany, the ST50, and it had 800 hrs of use before I started playing XIV. Fortunately, the IR is slight enought that it's usually not visible, but in bright scenes where the focus is on the periphery of the screen, it gets pretty distracting. I'm trusting Panasonic's promise that this should not be permanent, but I also think it will be a while before the IR goes away completely.

This game REALLY needs HUD transparency for this reason. The HUD elements are currently very bright, and I would imagine they could cause IR in playtimes of any duration. Given that MMO's are prone to long play sessions (not to mention completing a dungeon via Duty Finder can be a 1-2 hour affair from registration to completion), they need to implement this quickly.

I'll let you know what works for me. I'm currently using these videos to wash:
http://www.youtube.com/watch?v=LegAkKYOQTc
http://www.youtube.com/watch?v=L4gE_Xez-fQ