Currently the file is only used to detect the virtual project. Now that we have tsconfig.json support we can use the language service bound to a tsconfig.json file to find navto items. I would propose the following handling in case of the absense of a file:

• no tsconfig project. Command return no content message
• all projects are tsconfig project: return the nav to items (filter duplicates)
• there is a mix: the response contains a flag indicating that the result might be incomplete.