If we are lucky. The "Big Freeze" is really overdue. If this is the beginning of that, it could be a lot longer than 400 years, and a lot colder than the "Little Ice Age". In the chart below, "now" is on the left. Time runs from right to left.
You can also see that we are not as warm now as the peaks of the last few 100,000 year cycles. You can also see that the cooling tends to be just as fast as the warming was, for a while, and then it settles down to slower rate of decent.