I believe the Epcot tree was completely rewired either last year or the year before. I don't think it is going anywhere at the moment. The MK tree is in most need of a redo in my opinion.
I agree with you about the Epcot tree. I've never seen a photo of any 'burned out sections'. I'm betting that there's a decent upgrade in the works when they repurpose some of the Osborne Lights'. They've already been upgraded to modern LED standards.