He envisions people living in big glass-carbon fiber domes on the surface, with additional areas mined out below the surface by robots for "industrial" uses.
He said he had intended to announce his retirement last year but chose to stay on while BHP dealt with the aftermath of the Samarco mine disaster in Brazil.
BHP is not the first major player to flag green shoots in the mining industry. Caterpillar, the world's largest heavy machinery maker, said the same last month.
The deal, the biggest Canadian merger since CNOOC Ltd. bought Nexen Energy ULC in 2013, would create the world’s largest crop-nutrient supplier, worth about $36 billion.
Investors have seen a rise in the market capitalization of top junior mining companies on the TSX Venture Exchange by more than 100% compared to last year.
While met coal is clearly the star performer, thermal coal is probably the biggest upset – seaborne prices have jumped 65% in 2016 to above $80 a tonne.