Potential spoilers contained below, not because anything I'd like to happen will happen, but because I mention certain season 7 events in my theorizing.
I'll try to summarize as much as possible . . . I trust that given the fact that Joss Whedon made singing vampires work, and given that we've seen dead characters brought back time and time again, working this into a seamless, coherent tale should be near-effortless for the series writers. *grins*
I'm sure there are other loose ends, but I'd be satisfied with resolving these.