Those airlines that you mentioned would be welcome but are not expected to be the airports main users. It is 10 years out ( yes it will take that long to build) so any airline scenario is very speculative, beyond any business cases an airline would have in place. Even if they are planning that far ahead, none of them ever reveal core business plans.
But I can speculate ( totally unrelated to these airlines )
My informed speculation on the first tenants of the airport is this:.
The main users will come from the fallout of Toronto’s big squeeze. First to hit the wall will be city center ( 2024) then Pearson ( 2027-2030) runs out of all weather slots. The capacity of both Pickering to the east and Hamilton to the west needs to be ready for these users.
I am sure you can name the island users, but Pearson squeeze will pop some interesting point to point players over to Pickering. The discount point to point airlines not owned by air Canada or westjet is a longer list than you might think.
For obvious reasons will not call them out by name but finding an anchor tenant in each of the categories is not an issue.
All will be competition for Air Canada on both local and international routes, so they would be foolish not to then shift some flights to Pickering to compete for prime time slots.
One simply has to look at the traffic squeezed.
Here is the timeframe for the squeeze at Billy Bishop out of its latest masterplan:
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