The way I see it, Helmet toggle is never going to happen. The reason the downloadable armors can't have their helmets taken off is an art asset issue. They were created with an attached helmet, that means the art asset cannot be split into component parts, there is no way to make the helmet invisible without also making the rest of the armor invisible. Just to be clear, the armor in the chest are completely different art assets. All they did was take the armor asset and cut off the relevant bits to fit the look they wanted and packaged them as a different asset. They are not dynamic armor assets, they are basically immovable props, that just happen to look similar to the armors in the game.
There are two ways around the helmet issue, they take the downloadable armors and cut off the helmet of the 3D model and add it as another package to load. That means you could potentially switch between a helmeted and a non-helmeted version. Why wouldn't Bioware do this you ask? Because it doubles up on the asset making it an impractical and not sexy fix. It's basically a bodge job. I can see why they don't want to do it. It would also involve giving everyone a version of it for free because of the patch.
Now on the other hand if Bioware listens then what you are likely to see in the future is that downloadable armors will either A) not have helmets at all or

the armors will be downloaded in two pieces, one for the helmet and one for the body. Whether those full body suits will be able to incorporated into the segmented system used for the N7 armor, which would in theory allow for independent helmet control, remains another question. As far as I know the downloadable armors are controlled by a different system than the N7 system meaning that it may not be possible to have independent control over helmets.
I don't think you will ever see a dedicated helmet toggle system like ME1 had, that just isn't on the scope of what they would bother to fix, since the system is not essentially broken, just merely not working how some feel it should. Not saying I wouldn't like it to happen, I just don't see it as likely.