It takes time for things to set in.
2006 - PS3 will dominate
2007 - PS3 will come back and dominate at some point IF a bunch of things happen.
2008 - PS3 will get a solid second place far ahead of 360.
2009 - PS3 still has a chance to sell gamecube/xbox levels.
2010 - ... Umm, PS4 will dominate, repeat.