The world has changed that drastically that fast before. It only takes one generation.
Figure out how to really educate kids to a maximal degree. Post-religion anti-indoctrination memetic inoculation. Get everyone on the planet food. No anxiety around sex. Pain medication for anyone who needed it. Smarter technology. Less people living lives of quiet desperation. If all that stuff happens, people could get smart fast.
I think another shift the scale of widespread literacy is possible, and it might push the average center of gravity above the geniuses of the 20th century. Not the minimum. Oops.