As I read this, I was thinking of the early theories that any vehicle traveling over 30mph would likely be destroyed by vibration. So to read the first comment was amusing

"Clarke's First Law: "When a distinguished, elderly scientist says something is possible, he is very probably right. When a distinguished, elderly scientist says something is impossible, he is very probably wrong." In generations past, we've seen science magazines publishing articles explaining why heavier-than-air flight was unfeasible, why rockets couldn't function in vacuum, etc."

Nevertheless, being a skeptic, I tend to agree that it will probably never happen. It is such a massive project, with so many ways to go sideways. There is no reason to think that we will not solve gravity before we build such a thing.

In many cases technology renders big ideas obsolete before they get off the ground, (no pun intended). Certainly this happens more often than any failure to solve obstacles preventing us from accomplishing our goal.

A good example is terraforming Mars, a process that would take many hundreds if not a thousand years. The odds are pretty good that we will have ftl travel long before we make Mars into a livable biosphere, probably leaving Mars as "half baked" cheap real estate, suitable only for what resources Mars offers that can't be obtained cheaper from asteroids.