Regardless of whether or not a subject is tested, it is still important. Social studies is the collection of knowledge that our society passes down from one generation to the next, and it's extremely important that we continue to pass that knowledge on and create worldly citizens who can fit in and function in a global society.
Teachers will continue to teach social studies at all levels but students aren't stupid - they see what legislators value by what they put the money behind: math and reading. At my school, they ignored the social studies part of the MEAP test for years b/c it wasn't part of the MME. We'd have 70-90% attendance for the rest of the exam and maybe 5-10 kids show up the social studies test (that's not 5-10%).
One final thought: social studies continues to be one of the least funded major core subjects in America at the federal and state levels. We're not wasting money on it, b/c our politicians have deemed it not worthy enough to spend money on it.