Had a story idea

It was about human and pony versions of Rainbow Dash switching places and winding up in each others world but remaining as they were. Human Dashie remains human and Pony Dashie is still a pony but no one knows the switch happens. They think its a spell gone wrong then I realized nvm its an easy fix using the notebook that Sunset and Twilight use to communicate to each other. What do ya'll think? Good idea? Bad idea? Too many potholes in the synopsis to even bother with? Let me know what ya'll think or give me ideas to see if we can improve the story