Nobody
knows for a fact how this will turn out, and if they say they do they are lying and vastly overestimating their own knowledge.
There are no modern equivalents to compare to, so the best thing we have is the Great Depression; but when you look at the circumstances, it's not exactly a comparison that gives you a lot of confidence.
First of all, the GD had purely financial causes. Over-speculation in the stock market, high debts, combined with a struggling agriculture sector. As reality dawned, a mass sell-off took place that snowballed into what we now know as "the Great Depression".
If we for the sake of argument assume that what's happening now is exactly what happened during the GD, you still have to take into account how different the world is today. We are no longer in a mostly industrial, manufacturing economy. Our capacity for producing everything that keeps people alive is higher than it has ever been, which is another way of saying that our economy is more efficient than it has ever been. This is why most people can "get away" with not producing essential goods: many, many people work in "non-essential" jobs (for survival) like the service sector.
The only sane thing to say right now is that noone knows exactly how this will turn out, but saying that things will be worse than the GD is not only saying that the circumstances are way worse (that's absolutely not obvious to me), but also that our economy is weaker than it was 100 years ago, which to me sounds quite absurd.