There was a thread on here recently posted by a guy that was towing heavy with his 2500 (same truck as I have with the big block) and reports that likes his F150 EcoBoost V6 better. With the right engine, 6 speed trans, and a few suspension mods, wouldn't take much to make a single Suburban model that was economical for the soccer moms and also had decent towing capabilities, so no need to have a separate 2500 model in the line up.
The car mags are already posting spy shots of the redesigned '14 Suburban, so the brand is staying around for sure, the only question is whether they will continue to offer a separate 2500 model.
Would be great to see the Duramax/Allison in a Suburban...I know GM fans have been saying this for years....