Very sad. I have done a number of shoots there over the years and there were some very historic sets that are now gone. Fire is always a hazard on that lot, since most of the buildings and facades are made of wood. One only needed take the back lot tour to see so many instantly recognizable areas. New York Street is a huge loss, as is the courthouse square.
As much as I often rail at Hollywood for historical accuracy, they did some amazing things at Universal and I am saddened that something that has been a piece of my childhood and later life is gone. Yes, they will rebuild a lot of it and it likely won't be terribly noticeable, but the sense of history will be gone.