You asked why the future of Arthur Clarke's Deep Range hasn't come true. I told you, its wasn't about the technology not progressing, it was about the politics which prevent the business case for developing the technology needed to make it true.

We know how to train killer whales. GO to any SeaWorld. Or a net search on how the military is using them for military missions, And how to make ocean areas more productive. And so we could be ranching whales to feed the world. But whale ranching is not allowed so no one is developing the techniques and technology to do so. The whale ranching world of Deep Range is simply illegal by various international treaties.

The subs in Arthur Clarke's book are not that far from reality, except there is nothing to use them for, other then military purposes, and so no one is building them.

And if the U.S. was allowed to claim the moon in the 1960's, and sell the right to develop parts of its to mining firms as in the America west, there would be lunar mining today.

Regulation drives technology. The English banned experimenting with explosives fo the British Interplanetary Soceity couldn''t develop high powered rockets in the 1920's and 1930's. That is why they wrote about them while they were built in the U.S. and Germany.

If you want to develop space and build the rockets to do so then you need to create mining rights. Otherwise you will continue to read about it only in Sci-Fi.

To have technology you need to make it legal, or at least not outlaw the drivers of it.