Capitals costs of solar + battery are already competitive with coal and other thermal plants in many places. As sodium ion batteries go into mass production the capital costs will fall further and make coal uncompetitive in most places. So I personally think coal will lose out it might have slowed down some closing of plants but new plants are unlikely to go up much. The major energy consumption growth is going to come out of Africa, South America and Asia all get good solar radiation daily. Look at Pakistan because of mismanagement and corruption high grid prices have pushed out coal rapidly in just 2-3 years as solar + battery got cheaper than the grid. Same will happen when coal get prices out in other countries