While I support the West Metro, I don't regard it as a satisfactory augmentation of the existing rail corridor. It will essentially service a new rail corridor with what by their own admission will be an all stations service with up to a dozen stations between Parramatta and the CBD. Unless it is extended further west beyond Parramatta to at least Blacktown, then it will have minimal impact. So far, that possibility has not yet been flagged. The only way to ease congestion on current T1 line is to augment it with a new express tunnel from Granville to the CBD with possibly only one intermediate station at Strathfield.
Then there is the question of where the Parramatta Metro Station will be located, because that would have a bearing on how convenient it will be to interchange to the metro. Considering that the all stations metro service is unlikely to be any faster than the existing express service, then why bother changing unless your destination is along the new metro route?
There appears to be an impasse between the Federal and State Governments on the final recommendations of the Joint Western Sydney Rail Needs Scoping Study. The Federal Government appears to favour a north/south alignment between the SWRL at Leppington to St Marys on the Western Line via Badgerys Creek Airport, which presumably would be an extension of the existing rail network, whereas the State Government favours a direct metro connection to Parramatta, linking with the proposed West Metro. The State Government is reluctant to spend any money on extending the existing Sydney Trains infrastructure.
However, the Federal Government might have the final say in this if they are willing to make a significant contribution to the cost of a new rail link to the airport, on their terms.
New metro rail line from Sydney CBD to Parramatta 'highest priority' for state