Now NASA is full of pork.. You cannot kill it because . . . pork. In every congressional district.
NASA is not and never has been efficient. At one time that was irrelevant because of the nature of what they did. Now is is more about letting bureaucrats CYA when something blows up. And to make sure money flows freely to as many congressional districts as possible. The traditional contractors are not designed to be efficient either, except at maximizing how much they can suck from the government teat.
One way NASA might end is that with lower and lower budgets NASA simply cannot do anything. Alternately, they might end because they get budgets big enough to actually do something, making the real inefficiency clear for all to see.
NASA must be held to the same safety standards that commercial providers are held to. Otherwise, a culture of evading or ignoring those safety standards will creep in.
The only role that NASA might have left is projects that require large investment to overcome a lack of commercial motives. For example, going to Mars. Maybe for operating a space station. Probably not for mining asteroids.