This is a bit far fetched and I am not sure it would be possible at all.
It would be similar to djmicrons "modular insert" (which he pulled); where you could insert modular modules (m3, fleXor etc.), patch them up and have them load in any effect insert slot as a device. But it should work with regular devices like the OS patch-bay/router.
How does this differ from a MultiFx device?
The answer is simple: advanced routing like i.e. side-chaining.
I know you can load devices in modular via the effect insert, but I'm not sure it would be the same. I will have to experiment with that.