I posted a related Mark Moss video, yesterday: #671516.
I agree with him that it's more accurate to think of this as a slow moving collapse that began a while ago. There probably won't be anything like a particular day when the dollar collapses.
It's already lost half of it's purchasing power during the 21st century. The half-life of the dollar's purchasing power will likely continue shrinking. As the collapse quickens, more people will notice and head for the exits.
My guess at a timeline is that Bitcoin will be a major competitor to the dollar within the next 10 years.