UBER will wait it out and only do what's absolutely necessary.
Lets face it, there are a LOT of rides from the 905 into Toronto, and if the drivers that are forced not to operate in Toronto because of age of vehicle handle all of those and just deal with having the dead km back, and Toronto drivers cover most of what's required in the city they will do nothing.
I think it'll come down to where it effects UBER's bottom line that they will take any action.
If there aren't enough drivers and pax start requesting 8.0X surged poo during the $6.00 rush hour, and UBER has to cover the difference.... Action will be taken.
Of course the first thing will be to cancel the $6.00 rush hour rides.