There are a couple of issues here.
First, "library stafff" vs "librarian." The person who checks out your books, does the shelving, etc., is usually not an MLS degree-holding librarian, except perhaps in smaller libraries. They may hold another title, like "library assistant," "circulation clerk," etc. This is not to say they aren't talented/knowledgeable, but their job duties aren't those of a librarian. Librarians usually deal with more complex functions of the library: assisting with research, managing the scope and nature of the collection, outreach, programming, designing instruction, etc. Have a look at the description in the US Bureau of Labor Statistics' Occupational Outlook Handbook:
(Note that the outlook is actually listed as "favorable")
That said, the increasing amount of technology and self-service in many libraries is changing both how much staff we need and what roles we have those staff doing. Perhaps there will be fewer people at the check-out desk (we'll always need someone there to help solve billing problems, etc.), but they might take on other roles, like providing basic assistance in the computer area, helping with public programs, etc. Also keep in mind that, as long as there's a physical collection of books, videos, etc., someone's got to keep it in order, up-to-date, etc. That's a role jointly split between librarians and other staff. So, there's still a lot to do for quite a time to come.
Could everything go online and do away with the library? Again, not anytime soon. Even online resources cost money (since not every source wants to give their info away for free on the web). Libraries often purchase large databases of premium information that you and all your fellow users can use online and which go well beyond Google, etc. in their depth of information on certain topics. Librarians work to evaluate and select these, and then become experts in using them and teaching our patrons to use them on an as-needed basis. We're also shifting our roles, from working behind desks to doing more "outside" work--helping with research, teaching communities to be more aware of the information sources they use, doing chat and IM-based reference assistance, etc. So, frankly, we've got more to do--not less!
Also have a look at http://www.librarycareers.org.
And this CNN report: http://www.cnn.com/2009/TECH/09/04/future.library.technology/
Hope this is helpful!
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