They just revealed this on their Facebook page this morning. He's retiring from touring and will be replaced with Andy Sneap. Said he's been having early symptoms since 2008 and its gotten to the point where he can't play their most complex songs. A huge shame, but not surprising. He's in his early 70s and definitely deserves the retirement. He and KK helped shape metal guitar in the 70s so he deserves a good rest. That also probably explains why they put such a big focus on Richie. Pass the torch onto him.