I didn't notice any exponential growth of hosts in my home (although
my bandwidth grew from 14.4 to a T-1 meanwhile).
The exponential growth of _connected_ hosts was mostly fueled by
connecting existing machines and by new computer users. Unless
you have a recipe for getting people to breed much faster the
end of that trend is pretty much in sight (witness PC makers
killing themselves in scramble to the way-less-than-affluent market).
--vadim
PS. If you do know that secret recipe please keep it secret 