If it was possible to simply record audio in a track with None selected for the audio input, we'd be able to record soft synths in real time using the sidechain gate output method. Boom, just like that. No more new threads opening every week about the inability to record live soft synths.

well? anyone?

What an interesting idea.

I don't know if this would work (not at DAW to check) but pointing the track input at an input on the audio interface that hasn't got a signal coming in then side-chaining the VSTi into that track as well might work.

There might be a little noise made by the interface that gets recorded, but it would be no worse than the noise floor on anything recorded through the interface.

As soon as I arm a track for record, the input goes from None to Some  :)
 
Having nothing connected might work, but this necessitates having an available, unused input. 
 
Might as well throw a cable into it from an output ... nice thought though.