When the collapse will happen, people will be outraged and will pretend like in Greece that they were betrayed by their politicians, lied to. But this accumulation of debt happens in plain sight, it is just that no one seems to care.
Hard to predict the timig, like it is hard to predict the timing of a market crash. I have heard people calling the end of the current economic cycle for the past 5 years. Some say Trump has delayed a correction that should have happened this year by 2-3 years (if his economic package goes through). Well it's the same with the accumulation of debt. You can live on the credit card as long as your creditors are not concerned about your credit. At one point the sentiment turns and your credit lines get cut. Then it is the end. Greece is there. Italy is close. France and Japan a little further. The US will get there eventually.