I don’t think that splitting children up into those who are ‘gifted’ in the academic sense - presumably a coveted attribute - and those who are ‘non-gifted’ - presumably a less coveted attribute - is ever going to appeal to anyone other than those who see their children as belonging to the former category!
It seems to me to be an artificial way of distinguishing amongst children anyway. What does this sort of giftedness mean? What does being in the top X% mean?
I suppose it might mean that, in an IQ test, a child is able to achieve a score above a certain level. But intelligence is a multi-faceted, nebulous quality and who is to say that someone who scores well overall is more gifted than someone who scores very well in particular areas but struggles in others? And what about those whose thoughts are slow but they run deep?
In this respect, I rather like the Einstein quote: Not everything that can be counted counts, and not everything that counts can be counted.
It’s also true that, in many cases, the desire to identify giftedness, consciously making it a thing in the child's life and acting on it, is reflective of the socioeconomic standing and aspirations of the parents, and therefore any separating out of children of this sort would be de facto a separation on the grounds of class.
If you are going to split children up, and it’s a big if, I wonder if there might be alternative, more helpful ways of doing so...
Speculative
I’ve been thinking about this a bit because my DS has been struggling in his maths class recently. It’s more psychological than anything else. He is surrounded by articulate, confident, competitive boys who tease him for being quieter. Their loudness and extroversion make him feel less secure in his abilities. In contrast, he feels confident in the lower key environment of his physics class.
He is an introvert and does so much better in circumstances that suit this personality type. He’s actually in a selective school, a school that I suppose some might call a school for gifted boys, but if I had to make a choice between a school for the introverted and a school for the ‘gifted’, I’d choose the former for him!
(I wouldn’t be averse to streaming at this School for Introverts though, if required.)
Actually I have no idea if a School for Introverts would work at all, given that confidence and extroversion seem to be valued more than modesty and an unassuming manner in today's society, and there could be a danger of such a school being seen as a second class establishment. But I've been musing about it anyway as an alternative form of selection.