I agree that an open source Language Server would be desirable. Omnipascal looks great and even offers the ability to compile Delphi projects now. Someone else wrote a form designer prototype for VSCode. Put all the pieces together and we almost have a portable IDE with VSCode.
A language server would enable other IDEs to support the ObjectPascal language and enable EMBT to rip out ErrorInsight, and other parsers in the IDE. if they made use of it. If EMBT used an open source language server, the community could evolve and improve it over time rather than relying on EMBT. As a separation of concerns, it would also make it easier to get a cross platform IDE working, or multiple IDEs on different platforms. If you write code on OS/X and target only Apple devices, it would be nice not to require a Windows VM, or a PC as well. A language server might enable the use of XCode (not sure if it uses language servers) for ObjectPascal development.
At some point, a language server could enable Delphi developers to just use the command line compilers, and RTL to target their platform of choice with their editor of choice, and UI framework of choice.
https://github.com/alefragnani
Seems to have done some work along this line.