The train/tram line will not eventuate in the next few decades.
I grew up in Rowville, and even when I was a little kid they were trying to get the government to extend the rail line, I remember my parents even signed a petition at the local Post Office, that was 30+ years ago.
I also remember the idea of a monorail type thing being floated around the place when I was a teenager, running from Glen Waverly Station to Rowville.
There was also the idea of a tram line down Wellington Road or the extension of the tram line to Knox City down the Burwood Hwy.
The area is already well established and with Stud Park Shopping Centre getting a major overhaul (with a large bus exchange area) in the next couple of years, the 'train line' will be the last thing on the agenda for the next 20+ years.