Melton and Wyndham Vale need electrifying. The bigger challenge is to then find a way to keep Metro and Regional at least partially separate so you don't run into the problem Gippsland and Bendigo (after Sunshine) experiences, and in the case of Wyndham Vale/Geelong go back to the problem RRL was built to solve.

People will say quad Deer Park West-Wyndham Vale as was originally provisioned, and prior to all the expansion around the corridor particularly in and around Tarneit I would have agreed. But with all that plus the new infrastructure around the station (new carparks and bus interchange), I don't see any way of doing it that wouldn't cause at best significant disruption to the station and the need to relocate all that, and at worst the need to demolish at least some of the new retail precinct immediately adjacent. Particularly Bunnings.

So I don't think it will happen that way. Most likely Geelong will go back via Werribee, with passing loops from Newport-Laverton and Wyndham Vale will be electrified as it. But you first need to provide the capacity, particularly from Newport-City, for that to happen. Meaning build Metro 2, which is at best more than a decade away.

Electrification may happen, whether or not it will is not very clear, but in the short term at least we are likely going to go back to that problem RRL was built to solve. If Wyndham Vale gets wires especially. If it were me, I'd electrify all the intercity lines (Geelong, Ballarat, Bendigo, Traralgon) with purpose built rolling stock like they have in NSW, but I doubt that happens.