what does "make this/that/ fly" mean?

It's a metaphor from the invention of powered aircraft. During the industrial revolution life was changing quickly. Many people didn't understand the new fangled gadgets. Others thought they did and wanted in on making new inventions.

Many crazy ideas got pitched on newsreels but few ever left the ground. One thing everyone picked up on though was that an aircraft that has never flown is unproven. Once it took to the air and landed safely people gained a lot of respect for the design and its inventors.

Eventually "make that fly" or "get it off the ground" became expressions that applied to more than aircraft. So the question is a metaphor. It's asking if the idea will ever be proven to be viable.