Headline in a local newspaper of a small town. Nobody would care outside that town. And nobody in that town drives the decisions of a publicly traded airline. This is reality. Airlines change services all the time. Headlines don't stop them. And if AC needs those slots, that's exactly what they will do. Don't like it? Drive.
If a city like Ottawa (1.3 million CMA population) can't sustain a handful of 50 seater flights to Chicago (9.5 million metro population), I wouldn't hold my breath too long for half a dozen daily flights to minor centres all over Ontario and Canada. The pilot shortage along with rising fuel and capital costs is forcing average aircraft size up. A slot shortage at Pearson will merely accelerate this trend for Air Canada. Indeed, AC is already phasing out 50-seaters. In 7-10 years, AC won't fly anything from Pearson with less than 75 seats in it unless there's extraordinary yields. This would mean that a city like Sudbury would go from seven Q300s to five Q400s per day.
This costs money. Who is going to pay? Pearson already has a $25 airport improvement fee. Do you want to pay $50? They build in accordance with projected demand for a reason. And they work with the airlines to optimize that infrastructure for every dollar spent, which includes encouraging the airlines to make the best use of slots that exist.
They'd cease to exist. Simple as that. Those flights are fed by the rest of the network at Pearson. There's no business case to run the majority of those flights without that feed.
This doesn't even pass the common sense test. Imagine you have are traveling from Sudbury to London Heathrow. So now instead of a standard 1-2 hr layover, AC would have build in a 3-5 hr layover for you to collect baggage, catch a shuttle bus to Pearson, and check in and clear security again. If the GTAA ever insisted on such a boneheaded strategy, I would expect AC to declare Montreal as their major Eastern hub and move more of AC's European services there and force a lot more Torontonians to connect in YUL instead. Would be hilarious to see the unintended side effect of lots of Jazz flyers traveling internationally, facing a double connection in addition to that bus ride from Hamilton.
First, Waterloo and Oshawa are too small to handle substantial diversion of traffic. I've flown at Oshawa. 4000ft runway, hemmed in by development and border services restrict it to only planes with less than 50 pax. Waterloo is better. One long runway. But CBSA needs a 2 hr notice for any large commercial service operating in.
Next, no airline sees substantial commercial potential in either airport. Westjet chose to hub Swoop in Hamilton rather than Waterloo for a reason.
