I don't think it is to unify. I wouldn't be surprised if it would be another revenue source. People may prefer the interface of VS Code, but prefer the backend tools in VS. Microsoft could end up selling plugins/add-ons/whatever for VS Code.
That ship has sailed. Which programming language in the top 20 is commercial regards revenue from compiler, Debugger and nowadays basic LSP stuff like IntelliSense, code inspection etc.
The only commercial aspect is productivity like IntelliCode, IntelliTrace, GitHub AutoPilot and friends. For that you pay JetBrains, Microsoft, GitLab etc. There they will make money.
