- Use Common Lisp instead of Emacs Lisp. - Design a more modular architecture to make it easier to extend and maintain different components. - Design a more robust plugin system for development and distribution of extensions. - Implement better sandboxing and security measures for extensions. - Better APIs for extension developers. - better multi-threading support baked into the editor.
Why, pray tell, should this be of any concern at all? Sandboxing is used when the host is concerned about running programs that he doesn't trust. There is no reason that an Emacs package would require security measures around it, unless it were knowingly potentially malware. The only reality in which I could see this is if people were using proprietary Emacs extensions, in which case I would entirely understand it, because then people would be willingly running malware inside their editor. Perhaps this the stance VS Code users like to take towards extensions?