The only reason why I don't think she'll sing DS at the Duets finale is because the finale is only an hour long. Minus commercials that's only about 45 minutes.
I'm thinking she and Jennifer will do a duet. They are the last two teams and clearly the judges that brought in the viewers
J Rome, John, and Jason will probably get to sing with their mentors one last time. And I read on the other contestants' twitters (olivia, bridget) they'll sing too, plus they'll announce the winner, runner up, third place. That's not a lot of time for her to do a solo. Unless she does a duet of DS with Jason or Jennifer?
Or the contestants do a tribute to the queen
She is flawless.
About time 
