Well put, Metchosin/toadfrog
As to the future? Well, I can't speak for the FAR future, but I unfortunatley think shanties have had their 'golden age'. They'll still be around whenever the work calls for it, but barring some new developments in technology, I don't think we'll be seeing as much of a need of them as the sail trading fleets had.
However, there IS a fairly brisk trade in commercial sales of shanties as, well, entertainment. I know a couple bands who base a large part of their sets off of them - heck, a group I perform with does as well. Hopefully, enough people will stay interested to keep the old ones alive, and enough others will generate the occasional new one to keep the form alive.