In interactive mode, python.exe interacts with a console/(dumb terminal) through the std streams using \n as a special character  It gets input from stdin, send output to stdout or errors to stderr.  The terminal, not python, handles line editing and history retrieval.  Once a statement is entered and executed, python has no memory of it.

On Linux, one can use readline and ncurses modules for somewhat enhances interaction.

IPython is GUI-based.  Python already come with a GUI-based IDE, IDLE, which has many of the features you list - autoindent, statement history, save, line numbers in the editor, syntax coloring, and some source inspection.  Code with blank lines within statement can be pasted into an editor window and run either with or without clearing the shell workspace.

There are other alternatives with similar features, but this is not the place to discuss them.  The point is that there is no need to completely rewrite current text-based interactive mode.