I have heard that the reason 1918 was so bad was because, among all the soldiers in the trenches, it could be virulent and still be able to spread effectively, so it had no selection pressure to not be virulent. (If an illness is too virulent, it usually dies out before it spreads too far.)
Covid is a bit different, because it has a longer incubation time, and therefore has more time to spread before the spreader knows not to infect others, but that wasn't the issue with the 1918 influenza outbreak.
I’ve heard that as well and certainly hope that’s the case. But I’d think it’d be irresponsible for planners to just assume that’s what would happen, and not ask themselves what happens if the pandemic becomes worse.
Covid is a bit different, because it has a longer incubation time, and therefore has more time to spread before the spreader knows not to infect others, but that wasn't the issue with the 1918 influenza outbreak.
(Note well: I am not an epidemiologist.)