Imagine what would happen if Human is immune to HIV? Suddenly multiple sex partners would not be a problem anymore. The culture of free sex will prosperous. Prostitution will become a norm, even engaging in unnatural sex wouldn't scare people off.
Thinking along this line, developing a cure or vaccine for AIDS/HIV some how doesn't seem like a wonderful ideas, is like giving a immunity passport to the demon, allow it to wreak havoc among man. No hell for sinner, so you don't have to repent.
Otherwise this is a good news. (Link) Bill & Melinda Gates Foundation is pumping 15 million into the research for a HIV vaccine.