It seems that is early as 1964 Stafford Smythe and the Leafs had their eyes set on Vancouver: http://news.google.com/newspapers?id=NJ8tAAAAIBAJ&sjid=XJ8FAAAAIBAJ&hl=fr&pg=2801%2C1174554 Sure there is a much bigger story behind this.
forums.hfboards.com
Evidently the arena for this new expansion team (Canucks) was supposed to be Downtown (Vancouver).
Vancouver now has the 7th oldest building in the league at 27 years old.
The land is worth huge moola.
If they build another arena they will likely look just outside Vancouver, Surrey or Coquitlam, maybe Burnaby or Richmond but doubtful there.
Where ever it is it will be very close to Skytrain and highways with easy parking access. Another arena, hotel, casino complex. Maybe in conjunction with first nations.
Or maybe they move to UBC arena and sell 5000 tickets