I imagine the price tag associated with changing their defined "home territory" would be very high but not out of the question, considering that the Leafs arena sells out all the time (would not be affected to any great extent) and the marginal loss of revenues (TV/radio/media etc.) might make it very advantageous to the Leafs ownership to pick up a quick $100M or so from such a sale.
Don't forget that when Ottawa reentered the NHL, in 1992, they worked out an agreement with the Canadiens, that allowed Locally broadcasted games to be played in each other markets, and when they offered the same deal to the Leafs, they declined as they did not want Senator (Locally broadcasted) games shown in their market.
This agreement, with the Canadiens, brings in more eyeballs, for locally broadcasted games, for both teams, and more revenues as well. This is why Habs fans, in the Ottawa Market, can see all 82 games of their team, and the Leafs can only see the Nationally broadcasted games, that are not subjected to blackout, and vice versa.