A good example of a job that has gone the way of dinosaurs is an Armorer, a person who makes armor in the middle ages. Due to a change in technology things like wearing armor have become obsolete. This goes the same for many modern day jobs that may have the same decline soon. Such as video rental store. Already major companies are going out of business and it is getting more difficult to rent a movie due to changing services providing digital copies instead.
Although I do not believe this is completely true. Armor for an example can still be bought if you search hard enough. Authentic armor is still crafted in the same fashion as it was over 2000 years ago. So the services and skills never completely disappear just reinvent them selves to serve a different niche market.
It may be that in the next hundred years we come to see jobs and services we currently enjoy slowly decline and reinvent themselves to serve a different market.
Sources:
http://matadornetwork.com/life/20-jobs-and-services-that-will-soon-be-extinct/
http://jimsheng.hubpages.com/hub/Lost-crafts-and-extinct-jobs
