It's a business, if the others lack the other feature, the other will take advantage and add that feature that's needed.
While what you say is true, keep in mind that those small exchanges will not even account for 50% of the orders.
In such hypothetical scenario I can guarantee that small exchanges will not take that risk (or they do it but they
won't be able to sustain the demand).
It might be.
That's what I think and things can turn around in desperation when there's a serious demand that they can see.