Actually it probably won't. One of the primary reasons AIDS is a successful disease is because it's victims are infected, but otherwise healthy for years at a time and thus are able to pass it on. A strain of AIDS that exhibits symptoms and kills it's victims rapidly will soon die out.
I'm not sure the analogy with Ebola holds up. Even if full-blown AIDS occurs within three months, that is still three months that others can be infected, and others from them. And some with full-blown AIDS will continue to have sex while they are physically able.