Your entire premise is based on the assumption that the hijab is the problem, instead of looking at how people’s biases against Muslims is the problem. Who the f*ck cares what people in the future wear? If progress is important — then that progress begins and ends with changing bigotry, not changing clothes.
Worf wears a Klingon Baldric, signifying his Klingon roots. Bajorans wear earrings alongside their uniform. Counselor Troi wore a uniform cut to her preference as a Betazoid. There are many examples throughout the Star Trek universe of people wearing symbols of their own origin and culture along with their federation uniforms.
I see nothing wrong with the hijab still being worn in the future. Why do you have such a problem with it?