Yes, exactly, who knows? And this is pricisely the question, we don't have a clue. This unknowness is what's causing so much instability, the doubt, the fear, the horror, of where we might be heading, into a world we don't know, a world we don't understand or recognise.

I think, if we are ulucky, we could well see a slump on a scale that we haven't seen since the 1930's. In many ways it could be worse, as this is developing into a truly global crisis as the economies of the world are so interconected. What's happening? The world's economy is slowly grinding to a halt. Many sectors of the real economy are now, in reality, collapsing, on scale and at a speed not seen since the Great Depression.

How one get's the world's economy going again is a really hard question to answer. It may be a question with no real answer. I'm not sure Keynesian remedies will work this time. I'm not even sure they worked last time! If it was the second world war that really and finally ending the Great Depression, the creation of form of centrally controlled, state, command economy, preparing for war, then we have a lot of hard thinking to do.

I think "old-school" capitalism, the dogma of the "free market" is pretty much dead and buried. What we are seeing is the evolution, at speed, of new type of economy, a merging of state and market on an almost unprecedented scale. How this will influence the rest of society is too big a question to get into right now, though I do think it will have a profound affect.

"I'm not sure Keynesian remedies will work this time. I'm not even sure they worked last time! If it was the second world war that really and finally ending the Great Depression..."

I see this idea that WW2 ended the Great Depression repeated a lot. It depends on your definitions. If you look at unemployment and consumer spending, they still had not recovered in 1941. So in social terms, the Depression continued up until WW2 in the USA.
However, the stockmarket bottomed in 1932. GDP bottomed in 1933. It took a long time for the USA to climb out of that hole, but GDP grew in 1934,1935,1936 (recession in 1937),1938,1939 etc

Once FDR devalued the dollar against gold and started the big public spending programs, the economy moved to inflation and strong GDP growth (20-30% per anum) off a very low base.

I'm not saying this as a defence of Keynsianism. I'm just saying that in 1933 they conceived and executed a policy of engineering inflation, and they got inflation.

As for a "new type of economy, a merging of state and market" - it's all be done before, largely in the 30's. Public Works Administration, TVA,Civilian Conservation Corp, Resolution Trust Corporation after S&L. Recall the UK nationalisation of car makers, utility companies etc. There's nothing new under the sun.