Acid3 seems to be the ultimate pipe dream. It could be 5-10 years before the majority of Internet users are using browsers that pass it.
Maybe the version of IE released with Windows 7 will pass (IE 9?), but there are still people using IE 6 on Windows 2000, 7 years after IE 6's release (http://en.wikipedia.org/wiki/Internet_Explorer#Version_6) and 8 years after Windows 2000's release (http://en.wikipedia.org/wiki/Windows_2000#History).