First, can we clarify...What scenarios can push Melbourne CBD rental prices down? (other than oversupply)
I can't think of any other reasons why rental prices would come down?
are talking about retail, larger commercial and/or office, or residential (many apartments in Melbourne CBD)?
If the former, then much of what @Rob Legat - SBPL said above, I tend to agree with, although I wonder if parking is a thing in a CBD, compared to foot traffic?
One thing I do wonder about (your thoughts on this are welcome, comrade Birch...) is...
for those retailers who calculate return per square metre, in these tight retail times,
is it not in their interest to simply re-negotiate rent down,
so as to maintain that number?