Absolutely agree with VanBosh, EI will be mindful of what the data says in terms of where people are actually going, the most popular and profitable final destinations will be natural choices. I'd also suggest that EI need to be able to provide connectivity for the passengers who want to fly point to point especially to the most popular destinations like Boston New York etc. freeing up capacity on these routes ( ie by drawing pax to direct services) will allow them to also grow that business .
I'd expect new destinations could be chosen from the existing bases of Jet Blue or United. Is Montreal a possibility, they've operated there before, maybe be a suitable route for Boeing 757?