Governments and economies don't exist in a vaccuum, and there are always nations/forces in opposition to other nations (since the beginning of human interaction). So the expectation of say a Soviet Union lasting a thousand years instead of 70. The US and it's corrupt intelligence agencies aren't the only nations that maintain it's equivalent, even if some aren't as sophisticated, every nation has something like it. So any government or economy type faces the same challenges. So you cannot look at one or another system and pretend they'd become successful if they'd have been left alone. Humanity never leaves things alone, so your system if it's strong enough still has to survive in the wake of everyone else trying to stop you. That's a given, so not worthy argument to speak of governments in isolation, that's pure fantasy.
Capitalism is certainly seeing challenges, but I don't see necessary fall anytime soon. In fact, I see the world is at a turning point, and while the forces think it's going one way, the evidence that I see, is that it's going back to nation states, and the end of globalism. Religion is going to be a bigger part of every society in the next century, that's where the population will be coming from and urban secularism will die.