The biggest and most important existential question regarding AI is wholly different than what most people think it is. They are barking up the wrong tree.
Sentient AI is still pure speculation. It is so far off -- if it happens at all -- that it cannot be reasonably considered a viable threat. The people who actually work with AI, who are deep in the guts of it, laugh at the sentience speculations. They know how hard it is to just get simple things right.
In terms of existential threats to humanity, there is a far greater possibility of full or partial human extinction event born of advanced technological weaponry.
Think nuclear missiles powerful enough to take out the country of France or the state of Texas (Russia has one) or biochemical weapons capable of wiping out hundreds of millions to billions.
As for AI in respect to weaponry, far more worrisome than a Skynet hypothetical is the capability of AI-powered weapons in the hands of human generals. You don't need sentience for the rapidly advancing capability of weaponry to become alarming.
But weapons of war aren't the deep existential question that looms either. The real question is what happens when society becomes unequal to an order of magnitude and degree that has never been seen before.
The next big thing with AI is going to be humans interfacing with machines and software, enhancing human talent to a degree that has never been seen before.
Imagine if ten or twenty percent of the athletes in a professional sports setting suddenly became twice as strong, twice as agile and twice as fast relative to their peers. Everyone else on the field would be blown away.
That is what technological advances are going to do. They will not replace the human mind -- or if so, not for a very long time.
Instead, technological augmentation will make the most talented human minds -- the best knowledge workers, the best fill-in-the-blank -- multiples more powerful than they are now.
This extreme performance variation is going to rip traditional societies apart. You thought inequality was bad before? The top 20% of the income and talent distribution will go vertical with the help of technological augmentation. Not AI replacing humans, but the most talented humans using AI like a mech suit to enhance their unique human capabilities.
This reality is what is going to change the world radically, and quickly, and it is going to accelerate inequality like never before, to a point that old societal structures may not survive.
That is what is "next" -- the profound impact of dramatically increased performance variation as the most talented humans leverage that talent further via software, algorithms and machines, leaving the other 80 percent of the population in the dust. The sentience stuff is decades away if it ever happens at all.