It will be possible to disable the various actions that the diagram control currently supports. You can find them listed in the following help article: http://www.telerik.com/help/aspnet-ajax/diagram-rich-layout-interaction.html
Make it possible to drag RadDiagram shapes in mobile devices.
Add ability to define unique ID for each connection configured in a RadDiagram, so it could be referenced by this ID later.
I'm looking at using RadDiagrams for a dynamic workflow flow dashboard. I'd like to be able to format the text inside the shape with underlines, bolds and line feeds, etc. I'd like to see something implemented like in the report text box where you can pass in an HTML encoded string and when it's displayed it renders it as HTML. <b>Header</b>\n<u>Items</u>