A virus mutating to become less virulent but more contagious is normal
Not normal, there is no normal behavior for virus in general. The main theory is that if a virus kills its host too quickly it will not survive, or pass on to another host. Covid as we all know is not as deadly as Ebola, so it has a long way to go before it is immobilising its host before given chance to transmit. Some viruses have become less virulent, some maintained the same and our systems adapted. Others were vaccinated or became dormant, or died out, there's suggestion the black death is just as deadly now as it was back in medieval days.
However, to bite the bullet of your warning re the elderly, I would suggest that our economic ability to provide for this section of society (which was already under growing strain with retiring baby boomers and increased retired life expectancy) is dependent upon the younger part of the population being able to get back to wealth creating work that can underpin such welfare
Australia is far away from ever not being able to afford that, they could cancel the submarine program overnight and double the aged care pension and still have change.