After Voldemort is defeated and global wizard equality is achieved, the influx of half-breeds and less-capable wizards into Hogwarts and other magical schools grows dramatically. Criticisms of this change are met with accusations of bigotry, including calls of “you are starting to sound a lot like You Know Who with that talk!” This process continues, with miscegenation becoming “all the rage” for the next hundred years.
By the year 2100, magical bloodlines have become so diluted that very few people can actually use magic. Magical creatures find that they cannot communicate with students at school, wands begin to refuse ownership, and tensions rise as “pure” students begin to unite. The fear of a return to the Dark Days is still strong, and those critics who raise concerns over the decline in quality and use of magic are called “bigots” for their anti-muggleblood views.
In more progressive circles, prominent “intellectual” wizards begin to suggest that magic doesn’t really exist — not objectively, anyway. It is merely a social construct, and witchcraft and wizardry can manifest themselves in many different forms, most of which don’t involve the use of magic at all. This is met with great approval by the majority of muggleborns, though there is still discontent among those who continue to actually use magic “correctly”.
To combat growing discontent, the Ministry of Magic decrees that “flagrant displays of magic” are now illegal on school grounds, as this can result in prejudice and feelings of unwelcomeness for muggleborn witches and wizards, who are utterly incapable of casting spells (even those who manage to keep wands). The school removes most of it’s “applied magic” curriculum, instead replacing it with “Justice-Oriented Magic” and “Muggleborn Studies”, which focus on present-day social issues and the various expressions of “Alternative Magic” that are popular at the time, such as Ouija boards, Tarot cards, and divination of palms and tea-leaves.
Arthur C. Clarke, science fiction writer:
Any sufficiently advanced technology is indistinguishable from magic.
As the average IQ in society drops, engineering is going to seem increasingly like magic. For example, do you really have any idea of how your smartphone works?