The mind exists only in the mind, you say?
Where else would it be?
I'm saying that a brain is an environment where ideas can do interesting things (like reproducing themselves, mutating, splitting and recombining) comparable to the interesting things that started happening a very long time ago between amino acids and phospholipid membranes and assorted other organic chemicals which eventually resulted in the formation of brains. Any Turing-complete computer is also a sort of environment for ideas.
An idea outside an environment capable of supporting it does not do interesting things. It might be dormant, like a virus or bacterial spore, and colonize any less-hostile environment to which it's introduced. It might not. As yet, the only reliable way to distinguish between a dormant idea and a different arrangement of the same parts which does not constitute a dormant idea is to find an environment in which it will do interesting things.
For example, if you find a piece of baked clay with some scratch-marks in it, and want to know if they're cuneiform or just random scratches, you could show it to an archaeologist. The archaeologist looks at the tablet and compares it to prior knowledge about cuneiform - that is to say, transfers information about shape and coloration into her brain via the optic nerve and, once inside, drops them into the informational equivalent of a dish of agar. If anything interesting pops up, it's an idea. If not, either it's just noise, or it's an idea that the archaeologist can't figure out. There's no way to definitively prove the absence of potential ideas in a given information-bearing substrate.
If these disembodied qualia-properties don't help you make any actionable predictions beyond what physicalism could do, and their presence is unfalsifiable, I can't see any point to this debate. Is it a social-signaling contest of some sort?
Let's go back to your original statement:
A creature isn't conscious until there's a brain with a concept of 'consciousness' that identifies it as such.
OK, so according to you, we have concepts existing before and independently of consciousness, and we also have that consciousness is not a property that is objectively present (or else there'd be no need to appeal to the conceptual judgement of a brain, as a necessary cause of consciousness's existence). Both of these have to be true if you are to avoid circularity.
The second one already falsifies you...
...at least not if you accept a certain line of anthropic argument.
Thomas Nagel famously challenged the philosophical world to come to terms with qualia in his essay "What is it Like to Be a Bat?". Bats, with sensory systems so completely different from those of humans, must have exotic bat qualia that we could never imagine. Even if we deduce all the physical principles behind echolocation, even if we could specify the movement of every atom in a bat's senses and nervous system that represents its knowledge of where an echolocated insect is, we still have no idea what it's like to feel a subjective echolocation quale.
Anthropic reasoning is the idea that you can reason conditioning on your own existence. For example, the Doomsday Argument says that you would be more likely to exist in the present day if the overall number of future humans was medium-sized instead of humongous, therefore since you exist in the present day, there must be only a medium-sized number of future humans, and the apocalypse must be nigh, for values of nigh equal to "within a few hundred years or so".
The Buddhists have a parable to motivate young seekers after enlightenment. They say - there are zillions upon zillions of insects, trillions upon trillions of lesser animals, and only a relative handful of human beings. For a reincarnating soul to be born as a human being, then, is a rare and precious gift, and an opportunity that should be seized with great enthusiasm, as it will be endless eons before it comes around again.
Whatever one thinks of reincarnation, the parable raises an interesting point. Considering the vast number of non-human animals compared to humans, the probability of being a human is vanishingly low. Therefore, chances are that if I could be an animal, I would be. This makes a strong anthropic argument that it is impossible for me to be an animal.
The phrase "for me to be an animal" may sound nonsensical, but "why am I me, rather than an animal?" is not obviously sillier than "why am I me, rather than a person from the far future?". If the doomsday argument is sufficient to prove that some catastrophe is preventing me from being one of a trillion spacefaring citizens of the colonized galaxy, this argument hints that something is preventing me from being one of a trillion bats or birds or insects.
And this could be that animals lack subjective experience. This would explain quite nicely why I'm not an animal: because you can't be an animal, any more than you can be a toaster. So Thomas Nagel can stop worrying about what it's like to be a bat, and the rest of us can eat veal and foie gras guilt-free.
But before we break out the dolphin sausages - this is a pretty weird conclusion. It suggests there's a qualitative and discontinuous difference between the nervous system of other beings and our own, not just in what capacities they have but in the way they cause experience. It should make dualists a little bit happier and materialists a little bit more confused (though it's far from knockout proof of either).
The most significant objection I can think of is that it is significant not that we are beings with experiences, but that we know we are beings with experiences and can self-identify as conscious - a distinction that applies only to humans and maybe to some species like apes and dolphins who are rare enough not to throw off the numbers. But why can't we use the reference class of conscious beings if we want to? One might as well consider it significant only that we are beings who make anthropic arguments, and imagine there will be no Doomsday but that anthropic reasoning will fall out of favor in a few decades.
But I still don't fully accept this argument, and I'd be pretty happy if someone could find a more substantial flaw in it.