I agree, and it will stay true for a long time. Two issues, the first one small and improving : the smelting is energy expensive and does polute a lot. We're i

I agree, and it will stay true for a long time. Two issues, the first one small and improving : the smelting is energy expensive and does polute a lot. We're improving fast though, now that material scientific research got more credits. The big one: as we use more and more minerals, it's harder to find ore as easely accessible or as concentrated. If in the next decade we manage to build tidal/solar mining rigs, I'll be more optimistic about the future.