The big problem with scaling JS on the server is threading. There's simply no way to do it. You can spin up multiple processes, but then the communication overhead gets you.
The spec committee needs to bake in actors and they need to add tuples/records so sharing data across actors is easy and free. Finally, Typescript needs to bake in a warning to tell you when your code is going megamorphic so you can change it so the JIT can actually optimize for you (I think most JS devs would be shocked to find out just how much of their code is incapable of ever getting advanced optimizations).
The spec committee needs to bake in actors and they need to add tuples/records so sharing data across actors is easy and free. Finally, Typescript needs to bake in a warning to tell you when your code is going megamorphic so you can change it so the JIT can actually optimize for you (I think most JS devs would be shocked to find out just how much of their code is incapable of ever getting advanced optimizations).