After watching the discussion on the inter-webs and on general media, I have refined and developed my original thoughts into something I believe to be more workable and consistent with where the NSW government is going.

Tenders have been called for private management of a single-decker (probably driverless) service from Rouse Hill through to Chatswood (incorporating the existing Epping-Chatswood line).

The future plan is for that service to extend via an as-yet unbuilt tunnel under the harbour to central and on down the current Bankstown line to Lidcombe.

The above map illustrates a possible development that could be occurring concurrent with current developments, that would provide service improvements to more of the population in a shorter lead time with a minimum (though not insignificant) expenditure.

Instead of the eventual incorporation of the Bankstown line into the North West Rail Link, I propose the current Innerwest line instead.  Though realistically the T3 between Central and Regents park and what I am calling the T2 between Central and Cabramatta, are probably interchangeable.

Here is my thinking:

Capital Works:

• 4 tracks between Epping and Strathfield
• 4 tracks between Cabramatta and Granville
• Demolish Clyde, replace with 'Granville sprint' station on current rail property on East St, 150 mts from Granville - overhead walkway to connect similar to Flemington footbridge.
• Close (eventually remove) northern platforms at Auburn station.
• Close (eventually remove) northern platforms at Flemington and Homebush stations.
• Reconfigure northern tracks between Granville and Strathfield to allow faster transit.

Service Changes:

• L1 Epping Loop, high frequency, express to Strathfield to City then all stations to Chatswood.
• T1-west consistent limited stops to City then Hornsby and beyond
• L2 Liverpool Loop, high frequency, limited stops Liverpool via Strathfield and city to Revesby/Glenfield/Macarthur (alternate services stop at Ashfield/Burwood).
• T2 Cabramatta to Central via Strathfield, all stations.  Becomes southern end of NWRL.
• T3 Regents Park to Revesby via City/Airport.  
• T5 Glenfield to Penrith.  Passengers change for city service at major interchange stations. 
• T8 Hornsby to Strathfield via Epping all stations.

Track Usage, Central - Lidcombe:

• Northern pair between Central-Strathfield used by services going towards Epping.
• Centre pair Central - Strathfield, northern pair Strathfield - Lidcombe  used by L2 and T1-West services.  Possibly switch track usage within pair to ‘keep right’.  Would facilitate inbound services on T2 and L2 services being either side of same platform at Lidcombe, Strathfield, Burwood and Ashfield.
• Southern pair used by T2 Inner West service - tracks could be reserved for driverless single deckers similar to NWRL with a view to merging the services in future. 

Features:

• Epping Loop, Liverpool Loop and T1-west are higher speed, high frequency, limited stops services that ensure consistent travel times between major interchanges and CBD. 

• All stations with 20K+ pax per day (in and out) have direct service to city with 10 or less stops.

• 95% of stations (excluding on T4 south of Hurstville) can access CBD in 10 or less stops and max 1 service change.

The Sydney Trains network...

A few months ago I stumbled across a forum/discussion on Sydney's rail network - http://www.skyscrapercity.com/showthread.php?t=816926 which I found to be a really intelligent discussion of all things related to trains in Sydney.

In October last year the NSW govt made a number of adjustments to the timetable and line routings to improve the overall rail service.  Of course there were winners and losers, but overall I'd say the changes were a definite step in the right direction.

The forum discussions got me thinking how I would fix the rail network.

In order to make further improvements, there is going to have to be some serious infrastructure investment.  I think the govt already knows this.

If I were Gladys Berejiklian (NSW Transport Minister) here is how I might reconfigure the rail network:

The crux of the plan would be to turn the T2 line into a high-frequency express service from Liverpool through the City Loop and to Glenfield/Campbelltown/beyond and limit the number of stops for this service so that the highest number of commuters get the fastest possible journey.

And have a northern Express loop from Epping to Central via Chatswood and Strathfield.

The less-used stations are serviced by 'feeder' lines, that will probably necessitate one interchange to get to the city.  But over 90% of all stations on the network will be able to get to the city with 10 or less stops and no more than 1 interchange.

I would see the first priority to be upgrading the track configuration between Strathfield and Granville to permit express trains to pass through this area at greater speeds and perhaps higher frequency.
1. I would demolish Clyde Station.  It is only 350 metres from Granville Station and is really just there to connect the Carlingford line to the main line.  Very few passengers board or alight there, and there is property owned by Sydney Trains alongside the Carlingford line about 150 metres from Granville Station that I would turn into a 'Granville Sprint' platform.  An overhead pedestrian walkway could connect the two.
2. I would demolish the Northern Platform at Auburn Station, allowing through traffic to use the 2 express tracks at higher speed.
3. Currently there are 5 tracks most of the way between Strathfield and Lidcombe, although one of the tracks is not used for through traffic for much of the length.  I would add a dedicated a single track to the T3 line between Lidcombe and Strathfield and reduce Flemington and Homebush stations to a single platform accessing only that southern-most track.  Then have 4 tracks between Strathfield and Lidcombe to run express without any stations or unused platforms.

It will also be necessary to duplicate the tracks (ie 4 tracks) from Cabramatta to Granville and from Epping to Strathfield, so that express services can travel unimpeded by the local services.  The land appears to be reserved in both instances, but all of the stations along the routes would need to be rebuilt to cater for the extra tracks.

With the current Bankstown line and the Inner-west line, I would create 3 services.  Bondi-Junction to Strathfield.  Strathfield to Cabramatta (via Regents Park), and Central to Regents Park (via Bankstown). 

A train would take about 15 minutes to travel from Lidcombe to Strathfield and back to Lidcombe.  So assuming the frequency of service on the Cabramatta - Strathfield line would be 15 minutes or greater (which based on current patronage is a fair assumption), allocating a single track on that portion of the line is totally viable.

I chose to suggest that the Inner-west line extends to Bondi Junction and the Illawarra line joins the loop, because that would allow for the current Bankstown and Inner-west lines to use Vancouver-style driverless rapid transport trains in the future ie separating these tracks from the rest of the network (caveat: I have no idea how the tracks connect around Central).

Ashfield and Burwood stations would be too busy for smaller rapid-transit trains during the morning and evening peaks, but they are too close to Strathfield (and each other) to justify every express train stopping at both.  I would alternate T2 services between stopping at these two stations.

I have diverted the Cumberland line to terminate at Penrith instead of Schofields, to facilitate more express services for the major stops on the Western Line.

The Glenfield-Revesby line will become the link between Badgery's Creek Airport and the city if/when that eventuates.