I think we can't assume the reduction in consumption. After all productivity increase is not an end itelf but a means to sell more or earn more producing stuff

I think we can't assume the reduction in consumption. After all productivity increase is not an end itelf but a means to sell more or earn more producing stuff cheaper/faster. I expect that with increased productivity consumption will increase because people will want more and can afford more. As a result they will buy more, also due to lowering quality/durability. Low prices and efficient production lead to dispensable everything: clothes, devicesc car etc.