Of course the existing house will still be there if they're only building a new outdoor enclosure.
It's annoying that for years people have criticised Dudley and called for a new outdoor area to be built, but as soon the zoo tries to rectify it, with some fantastic plans, it's suddenly not good enough because suddenly the indoor area urgently needs changing as well. The indoor areas are actually ok for now. They may improve/extend them in the future, but one step at a time. The most important thing at the moment is the outdoor enclosures, you know, the thing we've been complaining about for years.
Finally, none of the orang buildings, including the moat, are listed in any way.