When the jobs go property values plummet - very very fast.
Ask anyone from Newcastle what happened when BHP closed down.
Same for any little mining towns.
Bigger places do not change what happens to the numbers.
Negative gearers find out how negative things can really be when all of a sudden half of their rentals become vacant. They try to save themselves from bankruptcy via auction and no one turns up! Then the insiders make a killing at a ridiculously low price in that situation.