I do not believe Mexico will nationalize any precious metal industry, so Mexus is out of luck. They will have to come up with the reclamation money themselves. Money they do not have.
Nationalizing the lithium industry is pretty meaningless and cheap. Any seizure of assets requires fair-value payments. There are no operating Lithium mines in Mexico, and the country is not a primary target for the metal. Sure, there are some prospects, but not much more than that. So this nationalization costs little more than the ink in the pen in which the bill was signed. And even then it doesn't mean Mexico will mine lithium itself. It just resets the industry and allows Mexico to dictate better terms to foreign companies to explore for and ultimately mine the metal.
Nationalizing silver, on the other hand, would cost billions and billions. Money which Mexico doesn't have. They also don't have the capital necessary to operate those mines on an ongoing basis. And I think they learned from the Pemex disaster - they are much better off taxing the industry instead of operating it themselves.