To be fair, it is possible to argue that many businesses of many kinds are directly or indirectly subsidized by the state to a greater or lesser degree.
Why bring this up? The dictionary definition of "sustainable" is here. Of particular interest are the second and third entries:
In business the first rule of sustainability is: "I have to be able to open the doors tomorrow." I know farming the government is a time-honored tradition and all, but at some point the field is no longer fertile, the turnips bled dry.2. pertaining to a system that maintains its own viability by using techniques that allow for continual reuse: sustainable agriculture. Aquaculture is a sustainable alternative to overfishing.
3. able to be maintained or kept going, as an action or process: a sustainable negotiation between the two countries.