Liam, you can already see that in the updated Master Plan. It's available on their web site (I'm sure).
I few links I found
Gold Coast Airport » Gold Coast Airport Pty Ltd Preliminary Draft Master Plan
and others....
http://www.goldcoastairport.com.au/downloads/fact-sheets/Fact Sheet - Development Timeframes.pdf
http://www.goldcoastairport.com.au/downloads/fact-sheets/Fact Sheet - Aviation Development.pdf
Aviation Business: Gold Coast Airport draft Master Plan released
Gold Coast Airport unveils 20-year master plan