wheel - 4:48 pm on Jun 26, 2011 (gmt 0)
No way, they're still going strong. As linkbuilder says, links stay, they just measure different attributes about links. If you remove SE's, links are still the roadmap of the internet.
Twitter might slowly measure in, but that's just another source of link data. And I doubt the SE's are going to tie their measurement of success on data from one single website, it's not comprehensive and too risky for them.
I don't see anything looming that's going to give as strong a signal of authority as a link from something like a strong .gov.