So their priority must have been to enable access to the SWRL for training / testing (rather than bring the northern flyover into use)
The next trackwork opportunity is the June long weekend (7th to 9th June). There isn't another one on the trackwork planner (which goes up to the end of August) that will allow the northern flyover to be cut in.
My guess is zero chance. With the SWRL in service, there aren't likely to be any services starting / terminating at Glenfield any more. Besides, there are a heap of projects recently completed that are getting rid of conflicting movements on turnbacks - I can't see them tacking something like that onto the well-planned Glenfield interchange (why build two flyovers and then put in a storage siding like that).
It is possible, I guess, that it could become a perway siding.
Yes, it does seem well advanced considering the opening date. It isn't unknown for things to start running prior to the "official" opening date (I would imagine that they would keep the official date reasonably close to the election, so that we all still remember!). Also, there's not really much out that way at the moment (the new stations are pretty much surrounded by commercial farming) and therefore not many passengers to use it (although I do think it's a good idea to build this sort of infrastructure before the houses come, as it gives people a chance to set the neighbourhood up for rail commuting - possibly new home buyers can give up one of their cars in order to help with the mortgage).
With the southern flyover apparently ready, I am wondering whether they will use the start of the SWRL to turn trains around (terminate on platform 3 or 4, turn around on the SWRL tracks, new service commences on platform 1 or 2). Maybe in a couple of months, when the signalling has been commissioned. This would also make sense as there is no track from P2 to the northern flyover, so they would need to move all EH line trains to P1 before bringing the northern flyover online.
The Leppington Junction OHW would be part of the SWRL project, so its completion at this time may be indicative of how far that project is now advanced, whereas the TCO would logically be a part of the G.T.I. project - different $ buckets, different priorities.
Amazed at the paucity of trackwork weekends you mention; it will be interesting to see what gets a mention in the February CU pdf's (if such there be).
A perway siding would also be a good possibility, given they lost the one that was at Ingleburn.
The size of the carparks at Leppington station could also be useful for commuters coming from as far away as Camden (and Oran Park,Gregory Hills,Catherine Fields,etc) rather than driving into Campbelltown.
Until an integrated timetable is introduced a Leppington shuttle would be a useful and easy start.
There IS a path from P2 to the northern flyover but it will need the new signal system to access it.
I've put together a small 14k .gif showing the track arrangements at Glenfield and will try to work out how to get it 'here' in the next few days.