We should remember that GDP doesn't reflect the totality of the economic reality on its own. It was popularized at a time of high population growth and the acceleration of mass production, presenting a perfect measure for encapsulating that time's idea of progress. As environmental threats are forcing us to reconsider our consumption habits with future products possibly created with less parts/materials/inputs, people may buy more used items, durability can become more of a priority where things are purchased and kept for a long time, GDP will go down. This however, doesn't reflect the diminishing of economic activity which takes on many forms, but is just one of the indicators which requires further contextualization.