clangd already has a layered architecture, where you can either use the JSON-RPC mechanism or more directly control clangd and implement your own transport. There are no plans for this to go away, as generally large companies often have environments in which they want better control of features than a standard protocol like LSP can give you, and we don't discourage that.

We also just talked with Apple folks at Euro LLVM about this, and while the plan for the near future is for them to have a transport conversion to JSON-RPC, I expect them to want the more fine grained control in the long term.