What is the cost recovery model in building this HSR system to connect KW to Toronto that makes sense if people can travel on it for $10?
Mass traffic. Big time.
By then, it is probably closer to $20+ inflation-adjusted. Again, this is frequent-commuter fare. Realistically I see it delayed-but-not-cancelled (a few can-kicks down the road) causing service to 2030s-2040s.
Historically, rail traffic spiked ultra-dramatically (in some cases, by over
two orders of magnitude -- depending on route) upon introduction of a frequent high speed service.
Not long after introduction, the TGV service in France got so overcrowded on the original route, they now run
bilevel high speed trains at
3-minute headways at peak.
The mass traffic economic case only makes sense when there's really good transit connection in all the cites served by HSR. This will become true in 2030s-2040s. Waterloo will have a wonderful 20+ years of TOD (Transit Oriented Development) by the time high speed trains arrive there, that is a LOT of new demand. Staggering and jaw dropping league.
Catching a HSR train in France and Japan is like tapping a Presto card and hopping onto the next train. In Japan, on some Shinkansen trains, seating is unassigned just like GO, on the economy coaches and you can be a standee on a Shinkansen train. Shinkansen use subway-style faregates, and some Japanese use the Shinkansen just like a subway. Tap, hop on, hop off, Tap out, done. Trains are more frequent than Sheppard Subway!
For Kitchener, it won't be quite that standard, but there can be allday high speed trains ramping up every, say, 15 to 30 minutes all day by 2050-ish as Kitchener/London goes through subsequent accelerated growth post-HSR-era.
The comparable population density for Europe high speed trains for a London-Kitchener-Toronto density, have their high speed trians running typically 15-30 mins peak and hourly all day long. So that's probably how it could be initially introduced as. Barcelona-Madrid is hourly offpeak, and 20 min peak. This is a very GO-train flavored high speed train!
Frequent commuter TGV pricing in Europe is similar to GO trains here.