I agree, I'm working with group manifolds and the coolest thing happened, I reduced the possible manifolds that might allow dS vacua to 4 (compactification to D=6, trying to find a toy model). It turns out I get almost exactly the same equations (unsolved for now) for each manifold. This suggests something deeper could be happening but I haven't seen it yet. (my advisor and his collaborators has a hunch but its far from conclusive) That's the deal with string theory and supergravity, often we have a feeling and need to investigate more but going deeper takes time (which I no longer have). I'd say the answer to the OP is that it's not dead but there are some issues we don't fully understand. And my opinion wrt other candidates for a theory of quantum gravity is that we need some authorities that know two of the theories very well. Who knows one could use ideas from other theories in whatever flavour they like best.