Things she didn't end up doing
Things that didn't happen
Spring, 1920: In spring of 1920, she was feeling better. There was discussion of a possible play, Mary Rose by Barrie. It was felt that Maude was really too old for the part of the particular character in the play. Frohman Inc. did not want her to play it. She was dropped from the play.
1921: “In early January, 1921, an announcement appeared in the New York Times, stating that she would return to the stage the following season, under the joint direction of A. L. Erlanger and Charles Dillingham. No specific play was named. (Maude Adams, an American Idol: True Womanhood Triumphant in the Late-Nineteenth and Early-Twentieth Century Theatre, doctoral thesis, 1984, Eileen Karen Kuehnl)
1930: The Joyous Adventures of Clementine: May of 1930, she signed a contract with A.L. Erlanger Amusement Enterprises, Inc. Should would appear on the New York stage in a “modern romantic comedy” directed by Williams. It was to be called The Joyous Adventures of Clementine. The project ended up being dropped.
1935: In 1935 producer John Godlen made a tentative announcement that in October she would act on the Broadway stage in an untitled comedy-drama by Adelyn Bushnell, but it didn't happen.
Evenings with Maude Adams: Maude was now 55. “Mr. Williams, a former stage director for Charles Frohman, began encouraging fifty-five-year-old Maude to attempt a stage comeback. With her consent, he contacted theatrical manager Charles S. Wagner who eagerly welcomed the overture. The three parties met and decided that Maude should make her reappearance in a program of dramatic readings and Barrie excerpts. To be called “evenings with Maude Adams,' it would tour select American cities beginning in March 1929. It never came to fruition. (Maude Adams, an American Idol: True Womanhood Triumphant in the Late-Nineteenth and Early-Twentieth Century Theatre, doctoral thesis, 1984, Eileen Karen Kuehnl)
Another play that was possible, but did not happen, was Arsenic and Old Lace. Maude turned down the role.
I have also found some material stating that Maude Adams was to be involved in the production of a movie verison of Kim. That material is here