Right now, you load the material into the machine with a small crane-like thing. So theoretically, I guess you could hook up piping instead. But that's still a honking big machine, and you'd need a machine that'd be larger than the things you're building with it, really.
I think eventually, it could happen. It's just not going to happen any time soon.
My favorite theoretical material supply scheme is grabbing carbon out of the air and re-configuring it into whatever you're printing with ;)
But anyway, this is pedantic details. We both get where each other is coming from.