Well, the evidence of airborne transmission in pigs and monkeys is very weak. There is some evidence of droplet transmission, but ebola is considered kids stuff compared with Flu. That could change if a strain evolves in the human population it's infecting right now. But it is extremely unlikely to evolve the ability to become airborne. The fear is more about evolving the ability to infect others while the patient is asymptomatic. That would greatly complicate things.
Right now it is thought that most health care providers who become infected contract the disease during the "doffing" (undressing) process. If Ebola were an airborne disease those protective cloths would do nothing and the whole hospital would be raging with viri.
Yes, I read the ~2005 paper on rhesus monkey airborne transmission and it was not compelling. As you allude to, a virus will evolve in a human to become less lethal, so it sticks around and infects people, the same way they say syphilis and small pox did. As for asymptomatic transmission, the other day I read (I'm not in the field like you, this was a blurb in the lay press) that an Ebola patient can in theory transmit Ebola up to several months after being infected through sexual contact, when the patient is asymptomatic (that was the gist of the blurb). So there's a fear apparently that perhaps the virus can be somewhat dormant in a post-Ebola patient and maybe infect others? Or that was my understanding. Anyway, I'm predicting disaster next year, and am 'stocking up' on my bitcoin.
TonyT