Agreed, structure editors must have interim/liminal representations that are only partially formed, or else the editing experience doesn't flow. I do think there's value in tracking the movement/mutation of AST nodes with the granularity and precision only achievable by a structure editor, so I hope someone cracks the formula.
One thing I think would be cool is if you could select a region of code and move it up/down the abstraction ladder e.g. convert an AST subtree into tokens, or all the way down to individual UTF8 characters. Then do some text manipulation on the plaintext, and finally "cook" them back together into AST nodes. The real cool trick would be to have the editor diligently track the flow of nodes/identifiers spanning the transmutation.
One thing I think would be cool is if you could select a region of code and move it up/down the abstraction ladder e.g. convert an AST subtree into tokens, or all the way down to individual UTF8 characters. Then do some text manipulation on the plaintext, and finally "cook" them back together into AST nodes. The real cool trick would be to have the editor diligently track the flow of nodes/identifiers spanning the transmutation.