It really sounds like what you are describing here is Nim. In fact, Nim even does per-thread heaps. It also implements a soft real-time garbage collector which

It really sounds like what you are describing here is Nim. In fact, Nim even does per-thread heaps. It also implements a soft real-time garbage collector which for most use cases avoids GC pauses. So I would say there is definitely at least one GC language that is worth using for systems level programming.