It's no hoax. There is an ongoing effort to redesign all of the 'Mechs whose art can no longer be used. PGI/HBS (computer games) and CGL (tabletop games) are currently doing their own, similar-but-different, designs due to licensing technicalities.
"Retcon" means "retroactive continuity." In its most common form, something was written years ago and forms part of the ongoing story. At a later date, it is decided that the "something" doesn't fit with the story after all, and the fictional events (or whatever) are literally rewritten. The term can also refer to simply expanding the backstory, where nothing is changed.
