Will we realise when our hegemony is over?

I wonder, in the late years of the Roman Western Empire, whether there was this consciousness that the best for them was passed, and that all they had left was to enjoy whatever were the leftovers. That would explain too the level of corruption in the late days (ok... here I have weak references, like a couple of films, but also some references from the Eastern Empire). They bribed the tribes that before were paying them, they did not maintain the order, nor police the empire anymore, they did not confront the problems of the economy and did not take the necessary reforms. And so, they died, one day... they were not the mighty Rome anymore. The city persisted, luckily... but the Empire was gone. And it was gone probably long long before the official fall in 476 AC.

We are told that they were because the economy was not strong anymore (mainly based in the work from slaves and the booty from conquests, it soon declined when these sources were over), because the Legions were not as mighty as they had been in the past (and were less equipped and had worse leaders and support), and because there was not enough internal political strenght, and famine and revolts were very common. And also, because the barbarians were pushing the frontiers like never before, pushed, we are told, by even more barbaric tribes.

But, where did these guys come? Is it possible that their weapons were so much better than the Romans? I think it was, but there was also a demographic phenomenon... the newcomers were mobile societies, very focused on war and very capable at it.

Anyhow, my main point here is that the reasons for the fall where there well before the fall itself... but nobody acted on them properly. The key was probably generating new sources of income and have the barbarians fight between themselves... but somehow the barbarians did notice the weakness of Rome. Today I see some similarities between Western way of life and Roman way of life. The economy is there, but lagging and not growing at the same speed as it used to. China, India... those are the powers of tomorrow... if they manage to gather the needed resources. It is not a small "if"... and China has a long history too of fatalities in their expeditions abroad. But in Europe and America we have this lack of vision of what is going on. We don´t realise that we cannot keep going on with our models like before.

I do not intend to be fatalistic, pessimistic nor anything similar. And I am not making an analogy between the fall of Rome and the potential fall or Western predoiminance. I am just pointing out the fact that a bad diagnosys is the key for bad decisions. And lack of initiative is key for failure. If we don´t realise that the tide of the wave is changing, we will not be prepared to mount and surf the next wave.

I wonder if the Roman citizens knew, in 450 AC that their way of life was only a generation away from finishing. By then there were already constant changes in power, constant wars and constant invasions and famine.. and it had been so since late IVth century AC. But did they know? And if so... did they react somehow?