that wouldn't work.
if the engine would be threaded, I'd think that there would exist thread for every entity or

Entity/Scene
Physics
Miscellianous (nature, sound etc)

But that alone would require the 'threader' to know how to avoid locks and how to keep everything in sync. Passing values in wrong way may chrash the program.

I'm targeting to the fact that you want multithreading without knowing what it is.