Times move on and with that so must businesses, which is what the Brisbane Lions are, a business. Obviously the Brisbane board think that the old logo and jumper where a little out of date and decided to change it to a more modern version. You would think a major part of this is to appeal to the younger generation rather then the generation which supported Fitzroy.
What about the principle involved? The Brisbane board in their arrogance has obviously decided that the passage of time entitles it to disregard the agreement. It's in everyone's interests that those making such decisions are called to account.