The release of Standard 189 and its possible future role relative to LEED are explored very well in this series of articles from Environmental Building News.
I think it's possible that Standard 189 (and/or the IGCC) could become a new lowest threshold that the most basic green buildings are required by code to pass. LEED will continue to exceed the threshold set by 189 and may increase its stringency. The other ASHRAE standards are likely to continue to be relevant.