Just to give you an idea, when Edwards died he left nearly 1100 sermon manuscripts behind. The 2 vol. edition, known as "The Hickman Edition," contains 66 sermons. When JE died the manuscripts went all over New England with relatives, etc. In 1905 the family decided to bring them all back to a central location, Yale University, so that they wouldn't be lost forever.
In about 1953 the late Perry Miller started the Jonathan Edwards Project, intending to have all of Edwards's works in print by 2003, the tri-centennary of his birth. That hasn't happened. Yale has done 27 volumes, some containing previously published material, much of it previously unpublished. And that is about half of it.
The folks at Yale have had to transcribe Edwards handwriting into a readable transcript, and then to make it readable to non-Edwardsian scholars. I spent two weeks at it and couldn't finish one sermon. So they have earned their keep, in my opinion.
When I had Soli Deo Gloria, we published 12 volumes of JE sermons, and many of those were unpublished up until that point.
There's plenty left to go!