Let's try another definition.
This is the one put forward by a number of Canadian environmental law organizations including Ecojustice, Nature Canada, and West Coast Environmental Law. Their proposed replacement definition would be:
Sustainability means protecting, restoring or enhancing the environment, equitably contributing to the social and economic well-being of the people of Canada, and preserving their health in a manner that equitably benefits present and future generations and that achieves mutually reinforcing, cumulative and lasting gains.