January 2009 marked the 6th anniversary of the launch of the Air Force Research Laboratory Solar Mass Ejection Imager (SMEI) instrument on the Coriolis spacecraft. Originally planned as a three year mission, SMEI has amassed an unprecedented dataset of ~25,000 full-sky images since 2003 with a 102-minute cadence, 1° spatial resolution, and better than 8th magnitude sensitivity. SMEI, with its Sun/Earth line views, has been joined by the twin STEREO spacecraft, launched in October 2006, whose heliospheric Imagers
(HIs) image along the ecliptic with opposing, off-axis views, 70° in diameter. These two data sets are complementary and several events observed by both SMEI and STEREO are being analyzed. But SMEI is nearing its end of life and the STEREO spacecraft continue to drift apart by 45°/year with decreasing
telemetry coverage. What would be the characteristics of the next generation instrument in heliospheric imaging? What would the differences be for an operational instrument vs. a research instrument? What are the advantages of staring vs. composite imaging, views from the Sun/Earth line vs. other views, L1 position
vs. low Earth orbit, etc? What are the engineering lessons learned from SMEI and STEREO and the environment through which such an instrument operates? In this presentation we discuss these issues and
some possible future mission concepts.