Consider this - perhaps the key to human evolution is the brain.
Most (if not all) people say that humans are the only creatures on this earth who possess full conciousness. Before humans existed, for about 4.5 billion years no living thing (on earth) had this ability. Conciousness wasn't a graspable concept. Conciousness is simply defined as one's ability to be fully awake and aware of one's mind and surroundings. This spawned all sorts of technological advances in the past 10,000 years, and to add to that, in the past 100 years we have advanced technology at a seemingly exponential rate. Conciousness can be attributed as the catalyst for all of this change; written language can be argued for this also, but that's not my where I'm going.
All being said, what if there is some sort of - for lack of a better word - "higher conciousness" ungraspable by the human mind. I wouldn't call it impossible. After all, conciousness is a result of approximately 100 billion nervous cells constantly interacting. Now look at the universe as a whole. All things observable to humans have some sort of interaction within itself - living or nonliving - and the environment. This scales from quantum particles that are the observable foundation of what is to the galaxies that light up the night sky. Considering there are 200 trillion galaxies in the universe all interacting with eachother, who is to say some sort of "unfathomable conciousness" doesn't exist. Being fully awake and self aware to itself and its surroundings would be a vast understatement for such a thing.
The human mind is simply incapable of understanding such a thing; it would be like trying to teach a dog conciousness. We can all agree that dogs possess some level of conciousness, yet they don't meet our standards by a longshot. Such a thing would be impossible for humans to even detect. Microbes wouldn't be able to detect the presence of humans if they possessed conciousness. We would seem like part of their environment, their universe; humanity to them would just seem like random interactions of their environment.
Humans can barely be considered a fraction of "what is", and what humans consider "what is", may be just as small on the scale of "all that exists". One could argue that it scales infinitly. The truth is that "what is" will be the only thing humanity will be able to understand, possibly ever. The unfathomable to the human mind will be pushed aside in favor for what can be proved of "what is"; we simplify it by calling it "is not" (non-existent).
Of course, everything beyond what is known by humanity at this time is only speculation. I can't conclude whether I'm right or wrong on the matter, since the nature of such a thing is incomprehensible; I can only observe what I see and speculate what it means. Worrying about the future of humanity, to me, is a wasted go, for there are things much larger than humanity out there. I believe it's silly to think humanity is so special, considering the scale of the observable universe; there is much more going on in "what is" than humanity. If humanity does continue to thrive as a species, I hope some day us humans will attain some sort of "higher conciousness". Anyways, that's how I feel on the matter.