So it sounds like Libra coins will be minted at a previously agreed-upon exchange rate by one of the consortium companies proving that they have bought one of these low-volatility financial assets. It does not sound like there will be any "mining" and the decentralization will be, for the time, in just a handful of large companies.

Can someone validate that I'm understanding that correctly?

If so, I'd agree with previous commenters that we're not looking at anything which can shift the power structure of monetary policy but improvements in transaction speed and cost could have some real social benefits - especially in the developing world.