Earlier quoted context omitted.
There's already limited evidence that some transmission is occurring via atomized saliva/mucous. A truly airbone variant could cause a "get in your bunker and ride it out" kind of event.
Usually the progression of most diseases is toward easier transmission but lower mortality rates. Viruses that kill their hosts have a hard time becoming endemic. My prediction for Ebola is that it eventually becomes like norovirus (stomach flu): a common gastrointestinal ailment that is painful and inconvenient, but seldom lethal, and spreads easily through contaminated surfaces.
Secondly, the mechanism of transmission of Ebola is quite closely tied to the cause of death. To be transmitted it needs to turn you into a massive viral factory and then make you very “leaky” so the virus gets spilled out into the environment. Any mutations that decrease mortality are also likely to decrease the infectiousness of Ebola
Thirdly, Ebola is starting off from a very high death rate. Even if there was a major decrease in the mortality rate (say it only kill 5% instead of 50 to 75% people), it would still be a huge problem.