Kingdom Hearts II When all that's left is darkness: A third type of Heartless?

As we all know, there are two types of Heartless that exist in the KH universe. We have the heartless that are made when the darkness in their own heart grows out of control, and consumes them. These known as Natural Heartless, and take on a completely black appearance, two antennas, and glowing eyes. They're often referred to as Shadows, but are also known as NeoShadows.
Ansem, albeit visually different, falls into this category.

There's also the kind of Heartless when a person's heart is consumed by some kind of darkness other than his or her own. Reference in KH1, on the first visit to Traverse Town. These are known as Artificial Heartless, and take on a much more colorful visage. They range in shape and size, bear the traditional Heartless insignia, and are capable of many amazing things. The glowing eyes, though, remain an ever constant.

But there's a third kind of Heartless which propose a new idea all together. When the darkness in a person's heart forces the heart free, but is unable to consume the heart, leaving only the darkness behind(I'd imagine). These Heartless, though never delved upon, appear in three different forms, are much more powerful than other Heartless, and have one common characteristic.
A Heartless such as this, would be a Heartless, without a heart. Ones that have heart-shaped holes in their bodies. In other words, Heartless of this nature, would be Darkside.

I stumbled upon the idea one day, while playing more of KH1. The idea, though never touched on in the games, is intriguing, to say the least. If a heart could escape its darkness, and join Kingdom Hearts BEFORE the darkness consume it, wouldn't that make an empty Heartless? Or Darkness in its purest form?
Sort of like a No-Heart.
The idea IS plausible, after all. Though I got to thinking, what kind of heart could do something like that? Perhaps a heart capable of wielding the Keyblade? After all, we know that a Keyblade Master's heart is very strong, but what if it was subjected to complete darkness, wouldn't it be able to bend the rules, much like now a Nobody can bend its shape, based on its will?
But Sora became a Heartless, right? Then again, Sora's darkness was self-inflicted, meaning that his heart was unable to escape that darkness, as it was surrounded and consumed by it, before it even left the body.

So, I'm going to turn this onto you guys.
Is it possible for a Heartless to exist without a heart: to be made up of the darkness of a heart alone?

 

It seems that your theory makes sense.

 

Personally, I never got the whole Heartless/Nobody thing. I understand how they're created and all. But the names are quite misleading. Heartless are created from hearts, while Nobodies come into (non)existence when the heart leaves behind a shell. In other words, Nobodies don't have hearts. But Heartless do. Argh.

As for the whole thing with Darkside, I agree with you there. In the first Dive into the Heart, Darkside was spawned from Sora's shadow. A really cool concept if you think about it. :p