Well, should they, or when they, get one working...get back to me. It will be an historic and monumental day, but I am not holding my breath.
Why not? We'll just come back in our time machine and revive you.
Tesla made an Earthquake machine. Who knows what has been invented and kept under wraps.
But, I doubt anti-gravity is one of them.
Thoughout history there have many "eureka" days. Add to that...many devout Christians believe that He walked on water. That is a belief in levitation. Peter levitated also.
Nothing is impossible that can be imagined. The history of science tells us that. Of course, the jury is still out on time travel and a few other things. But what does the jury know.
I can't remember the source but I do remember that some authoritative group of scientists said at the end of the 19th century that science had discovered all there was to discover. And someone else said that a heavier than air machine could never fly (I guess he wasn't a bird watcher).