The subject is relevant, though I don't recall seeing anything on it posted.

NASA is also looking into the possibility of water on a moon of Pluto. Both are scientifically interesting, but not realistic as resources for extraction.

It's bound in the structure of a mineral; as a contaminant, it lowers the melting point of the mineral and dissociates to produce some intermediate product.

Partial melting is something that's been examined rather intensely at shallower depths. The kinetics and mechanics at those depths aren't a great mystery; more like "let's work out the details and see how to use them in refining our models."

It won't ever be useable in any way it's not useable now. Water is subducted at convergent boundaries. The mantle's fairly mixed--it's heterogeneous at a small scale, from crustal fragments that haven't dissolved fully, but there's no reason to suspect that it hasn't reached steady state. It's likely that some of the molten material makes its way up through plumes, so some water is returned to the surface through volcanism. There's no reason to suspect *that* hasn't reached steady state, either.

The problem is how "oceans" was used in the pop sci press. It made it sound like the water was found in discrete units, rather like oceans are. As though if we could drill deep enough, we'd hit a geyser. Instead it was a quantifier, "quantities large enough to yield oceans" of water if it could somehow be collected from the vast quantities of mineral it's bound to.

It's just interesting stuff that helps us understand our world a little better.

Like Quixote wrote, it adds to our understanding of our planet. You're getting
worked up over nothing.

2/3 of the surface of the planet is covered with the stuff, in some places literally miles deep.

There is no shortage of water. There is from time to time and place to place a shortage of cheap water. That is all.