The official line is there's no special relationship between Motorola and Android beyond a common owner; thus they have to bid on Nexus devices like everyone else (and so far, there's nothing to suggest otherwise). As well, there's restrictions on how companies in the middle of an acquisition can communicate, which would make a Motorola-produced Nexus this cycle particularly difficult.

We can also see that there's no connection in the lack of up-to-date Android on Motorola phones.

The carriers get as much blame in Android's update SNAFU as the OEMs (and Google, by inaction[0]); the VZW Galaxy Nexus demonstrates this.

[0] While Google could have taken a stronger stance on Android re: updates, I don't think they've ever been in a good position to do so. Early days, carriers would have balked and Android would die; now, they'd just fork and Android becomes the next BREW.

In my case the OEM is to blame as it is only company I can associate my phone with (bought it without a contract in a store). So it probably depends from whom you bought the phone and under what conditions.

Besides the silly wall between the divisions, the Nexus 4 was probably designed before Google bought Moto.