Key quote: Given the right conditions, new sexually transmitted infections can emerge and kill you and all your friends.
If we ever beat HIV and AIDS, that doesn't rule out another bug from evolving or crossing species in the future. Eddie Murphy once had a routine that talked about this comically: "you stick your dick in and explode!" Think about it. There's no reason something couldn't happen after HIV, and there's no reason it wouldn't be worse.
Also: "and stay the fuck away from meth and meth users."