Allow for the user to select the type of geodatabase to be created by default with all new projects.
Currently a user can select a file geodatabase or mobile geodatabase to be the default for a project AND select a singular geodatabase top be used by ALL projects.
This idea would extend that same choice to the default geodatabase created with every new project (if your project settings are set to create a new geodatabase with every new project).

The natural evolution of this project:
Mobile Geodatabase as Default - Esri Community