The comments made suggest they don't want to completely remake it, they want it to feel like the same place just fresh. Like, Draenor Nagrand, despite being the closest zone to its original, still feels like a totally different zone.
I think the changes will be largely in the the texturing, polygon count, etc. Maybe some terrain touch ups, like in Cata where they fixed rivers to not be so impossible to get out of when you fall in, and made hills make a bit more sense, etc. I expect expansions will be on the ZA side or filling out the north of SMC, but most of Eversong and Ghostlands will remain as is but nicer.
I really think Cata is what people should be expecting. Like go take a look at Vanilla WPL/Trisifal/Silverpine, and Cata WPL/Tirisfal/Silverpine, and expect that.