It can if you have actually isolated busses feeding into what I will, for lack of knowledge of a better term, a CAN router. Maybe it exists, but I'm imagining a device with multiple CAN inputs that makes decisions on what messages to pass on to other busses.
That what gateway is doing and that's the reason why they are going for headlights (which are sharing bus with immobilizer I suppose) and won't go for door locks or TPMS.