The way the science community uses the term ‘rare’ with these elements is misleading to most. It’s not like baseball cards, with common, uncommon, and ‘rare’. It’s not like that.
Rare in this instance pertains to the difficulty of extraction. A ‘rare earth element’ is much harder to extract, therefore much more expensive to obtain. I don’t think it means there is a shortfall.
Change the value of Thorium and this changes. China values the Thorium radiation liability at zero (along with all the other environmental liabilities of mining) so willingly mines most of the world's production. Theoretically Thorium can be used in nuclear reactors to produce loads of valuable electricity, and along the way expend its radioactive liability. Moreover, Thorium reactors can theoretically profitably destroy several other sorts of radioactive liability. The science behind Thorium reactors seems solid, but engineering and experiential proof is limited. Generic nuclear power environmental laws, driven by mindless liberal fears over Uranium reactors, currently block them in this country. China is actively pursuing the Thorium dream of cheap, abundant, probably safe, power. Proposed US legislation could unblock both US Thorium reactors and US rare earth production.