This is all nice, but until Metrolinx pays CN the 1 billion or so to get the space in Brampton GO they cannot expand service imo.
They absolutely can expand service. For an hourly service to Kitchener, the next train meet to the east of Georgetown would occur at Malton station, which also happens to be where the current hourly service meets. So outside of peak periods, GO only needs a single track through the largely 3-track CN corridor. The lack of 3rd track at Brampton station simply means that CN has a short segment of single-track operation if they happen to arrive while GO is occupying the second track.
Until a flyover is built, the options for an hourly service west of Georgetown are: meet on the GO line and disrupt CN traffic twice per hour, or meet on the CN line while crossing CN traffic, which only disrupts CN once per hour.The "plan" has changed so many times I have lost track of what lies ahead. But fundamentally, you are correct - the southmost track (South Main Line in CNspeak) could serve as a GO platform as well as a VIA platform. The "If" is whether CN would allow two trains to meet in a way that ties up one of their main lines every hour.
The odd thing that limits operations currently is that the GO platform track has an unsignalled segment. This forces the signals governing entry to the existing GO platform to display speed-restrictive indications even when the track is clear. After stopping, trains must maintain that low-speed creep until they reach the next signal. If that were corrected, GO speeds would improve. And if power switches were added, GO could have a two-track passing area in its existing station. That's not all that expensive an upgrade.
The flyover BCS suggested that a meeting point west of Georgetown station was needed. That makes sense to give a couple minutes' contingency, and it keeps the meets off CN's turf.
Kitchener Expansion BCA 2021, page 19:
I would have thought that resolving the signalling through the platform would provide sufficient schedule padding for the meet to occur at the platform of Georgetown station. Guelph-Acton and Acton-Georgetown are both scheduled for 15 minutes, but Guelph-Acton is 21 km (84 km/h avg) while Acton-Georgetown is only 10 km (40 km/h avg). I figured that a big part of that discrepency is the current slowdown in Georgetown.
During peak periods there would also be an intermediate meet at Acton between the hourly counter-peak service and the extra peak-period services which improve the peak-period headway to 30 minutes. But I figure that a couple extra minutes of padding could be freed up for that additional meet by having those extra peak-direction runs skip Acton station - thereby cutting their travel time by 2 minutes.
It looks like it would be quite difficult to get a fourth track through Silver Junction, so unless they were referring to the future passing track at Acton station, a passing point west of Georgetown would presumably be a standalone passing siding, which would be disappointing since passing places between stations tend to produce more delay than passing tracks at stations where trains need to cross anyway. If the travel time is still too long then I'd prefer that they extend the double track east from Guelph Station. Surely adding a second span to that bridge is affordable - it should cost less than the current work they're doing to replace spans and crossbeams.