It won’t nationalize the mining industry. On the other hand, the constitution would grant indigenous groups autonomy over ancestral lands with their own justice systems; which means that indigenous communities would be have greater say over the investment projects near their land. Also, mining industry will be more regulated regards to environmental issues.
source: https://www.wsj.com/articles/chilean-voters-are-likely-to-reject-constitution-overhauling-economy-11662202801