I've been wondering - would it be possible that something like HIV comes along, only airborne? This would be a nightmare scenario obviously, but is it possible?
For example, by “something like hiv” do you mean something that acts very slowly, but eventually kills you? That indicates a low viral reproduction rate - which means you’re spreading far fewer virus particles than something like covid, thus a low transmission rate, even if airborn.
Do you mean “attacks the immune system”? How does it get airborn, if it’s in the relatively few immune cells in the lungs? I suspect if you inhaled an aerosol of hiv particles you might catch it, but it doesn’t have a way of getting in the air.
Again, not an expert/wild speculation, but I think the risk of something fast acting, highly transmissible, and highly lethal, is more of a concern than a slow-acting lethal virus.