i would think there would be more demand from YVR, especially for leisure travellers, at least vs. YYZ. For families going to Disneyland, this would be easier than LAX.
And I think there would be more demand from westcoast to SNA than out east. From what I understand familes out east primarily go to Orlando / Disneyworld vs. Orange County / Disneyland.
However, article didn't indicate that WS was looking at YVR-SNA or what the route would be, assuming all approvals occur.