I hope all members of the community are interested in working together on a combined effort. Several people have invested time into solutions in this area.
One of the things that I would like to emphasize is that more of the Swift tooling support in Xcode currently supported by SourceKit will have far more of that core functionality in the open source service (e.g., the global index and global refactoring operations) once we move to an LSP-based implementation. @akyrtzi mentioned this in the original post but that important nuance may been missed. Consequently, the LSP service @akyrtzi is describing will be functionally more powerful than SourceKit is today.