So many under educated muppets on here ramble on about how inefficient the B717 is and how it's be replaced by a jet that has 70+ more seats. Please do us a favour, go back to uni or where ever and learn about RPKs, fuel burn, etc etc. go read about the B717 and how other airlines use it and what sectors it does.
There's obviously a market in Australia for an aircraft of that size, not all want or get a B737 packed to the brim on every sector and we all know what a lot of pax think about anything with those spinny propeller things.
Having said that, Qantas will obviously take back the B717s into network. as for Cobhams days numbered.......once again, go get educated.