There is no inherent reason, according to Hayekian economics, that a nation cannot prosper with a steady population, or even a shrinking population*. The true reason many nations like Japan, Italy, and others is because they’ve set up a government “Pyramid Scheme”, to make the young generation pay for the taxes that benefited the previous generation.
Most nation’s government’s do this trick.. and then when things eventually become unsustainable, they require more young suckers, to feed into the system, to keep it from sinking (or more immigrants). In fact, a shortage or workers could actually increase wages due to demand. (of course with extremes, productivity would be hurt).
To my fellow Italians… don't believe this excuse…. its a bandage masking deeper economic problems.
* (assuming its slow and gradual population decrease, and doesn't exceed certain thresholds… maybe 20% to 50%)