https://www.imperial.ac.uk/media/imperial-college/medicine/s...
There are 40 million 40-somethings in the USA, you're proposing that 100% of them will have lung damage.
Let's imagine that 80% of the population is infected, that 80% of cases are symptomatic, and that 80% of the 4.90% of hospitalised cases (this 4.90 is direct from the report) get damaged lungs. This is one million 40-somethings, not the entire population.
1 million sounds like a lot, but its only 2.5% of the population at that age range, and assume worst-case.
You know what causes reduced lung functionality in adults? Asthma, driven by air pollution from vehicles and coal power plants. 7.7% of adults have Asthma. Where is the war-scale drive to eliminate fossil-fueled vehicles and power generation?
Vaping. I see most of the young adults doing this. Its probably why they're having the higher hospitalization rates with coronavirus. They already have lung damage.