It might as well be a blank card. He can play it if he wants, but it doesn't mean anything because it's as empty a threat as there could possibly be. It's not unfathomable that moving could make more sense financially, sunk costs and all, if they don't get the concessions on the things they're asking for. It's almost unfathomable that they would end up moving, which is why opponents should view the threat as nearly empty. They would literally have to get nothing they want to justify such a move. A top rate stadium is going to start at $1B, and construction would not be able to begin for at least a year, lasting another 1-2 (at least). This would require essentially spending zero dollars on Wrigley Field for the next 3 seasons, while still playing in it. You can't justify a clubhouse upgrade, any sort of expansion or new signage. You would have to remove the city from negotiations for the new land, which reduces the competition by the suburbs that want in. If they get 50-60% of what they want, they probably can't come close to justifying a move to a new location.