It may impact IE7 more than it does IE6. In fact I believe IE7 usage will fall below IE6 in relatively short order. Those who have not left IE6 are mainly in situations that prohibit them from moving on to IE7/8 without major pain (operating system, intranet applications etc.). As long as these are not remedied by IE8, IE6's share will not drop drastically. It will just continue to decline, perhaps at an increased slope, especially if web devs start leaving IE6 behind as well, but no funeral invitation just yet.