Even thought the 2010 Astro Decadal Report's Executive summary does not recommend SIM as a mission to be pursued, there are other voices in the astronomy community that differ.
The first document that differs with the Astro 2010 Executive proposal comes from one of the Focus Panels of the Decadal Survey itself! Take a look at the EOS Panel Report. On page 6-7, the panel reports on previously endorsed projects. It notes that SIM was re-endorsed by the 1990 Decadal Survey recommends it as a candidate for NASA's Exoplanet mission.
On page 6-34, the EOS Panel is even more explicit. To quote the report, "The panel is enthusiastic about one such program, SIM Lite.."
With a recommendation such as this from the Panel that was charged with surveying the ExoPlanet mission outlook, it is surprising, to say the least that the Executive Summary essentially ignored SIM.
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On another front, a recent presentation by M. Fridlund, titled "European Roadmap for Exoplanets," has a very important observation in its summary. This page, "Conclusive Recommendations," makes it quite clear that an Astometric Exoplanet mission is on its list of 3 "High Priority" missions. Here is the relevant quote from that report -
"We can identify 3 "high priority" missions types:
An astrometric mission to find terrestrial planets"
It appears that the author is somewhat baffled as to the "demise" of SIM. I think that the same can be said for many Exoplanet researchers.