rescue 1,
These are the facts:
VB are taking delivery of some 800's in 2009 (can't remember exact number)...remember these have already been signed up/paid for.
Some 700's are going back after lease expiry in 2009 (again no numbers)
Sydney slots are at a premium and as it stands flights to ML/BN run at every 15 mins during peak periods.
The rumour is:
900's offered in place of the 800's due next year as slots have freed up.
As you can see, there won't be an increase (or very little anyway) of 737 airframes in the sky but rather increased capacity coming from the 900's which is desperately needed.