I do, as well. For some parks, self-sufficiency will be difficult. Within any state, there are parks that are heavily used - those near larger metro areas, those with special features like lakes, good hiking trails, waterfalls, nice campgrounds, and year round attractions, e.g.
Other parks, many in rural areas, which might be just pleasant retreats for a day visit when the weather is nice will find it difficult to survive.
I don't think EACH park has to be self sufficient. They busier parks will subsidize the less busier parks.