I checked the status cache and it could possibly be done in a separate thread there, with the limitation that what you see in Explorer would be "old news". There is an issue of knowing which repositories to poll - on my computer I have probably 100 different WCs (different repositories or branches). It would be completely waste of resources to constantly poll all of them so some kind of queue has to be created based on which WCs you work on. On the other hand when you open a WC you have not visited for a long time, the cache would be cold and the status would not be correct until next polling intervall (making the status rather useless).
To summarise, I think it will not be very useful and I think other issues have higher priority. However feel free to take a look at the code and come up with a solution.
Kind regards,
Daniel Sahlberg