It's a virus that replicates inside of blood cells. If it were to "become airborne" it would be a fundamentally different virus. Viruses are protein coated DNA or RNA that attach themselves to certain cells they were made to attach to, replicate, then burst/destroy. It isn't going to "become airborne," like the flu or something. Fundamentally different ways of existing and spreading. It's like saying HIV/AIDS is going to become airborne. The odds are more than 0, but so infinitely small that it might as well be 0. Period.
The number of people one sick person will infect is called R0, it basically means reproduction number. Ebola's is R2, meaning one person will infect on average 2 other people. That's still pretty damn scary but with the amount of protocols that we have in place t just isn't likely to be a huge issue. We have the resources (disposable equipment, cleaning supplies, incinerators, hospital isolation areas, knowledgeable staff that have been practicing universal safety precautions for years, proper hygiene practices) that many parts of West Africa doesn't. We also don't have a cultural practice of washing our dead. We also don't have to deal with random people we've never seen before showing up to poke us with needles while wearing huge yellow suits, speaking in a foreign language, and taking our family away only to report that the family they poked with a needle and took away was dead and we can't see them ever again. It's not going to spread the way it has in W Africa.