Viruses - Contact to Airborn

[Keith Sturts]

These kinds of speculation make for great stuff if your are 
interested in thrilling movies, books, and the resultant 
misinformation resulting from the fictional aspects of these 
stories.

Has there been any speculation, any prediction of the really 
deadly viruses, i.e., hanta, aids; going from contact to airborne 
in method of invasion?  Or is that possibility completely 
unknown?

Is it now more completely understood it would be unlikely that 
most viruses, life-threatening or not, would or could evolve in 
method of spread this way?

If one of the more deadly viruses did eventually become able to 
spread via airborne method, wouldn't this threaten the continued 
existence of the organism susceptible to invasion?

Is there any record of microorganisms, multi-celled animals, non 
vascular or vascular plant species being completely eliminated 
in this manner?