This needs some deeper thought.

Invisible things would show themselves in front of eyes naked from the "clothes" of prejudice, bias and personal experience. Visible things would disappear also, stereotypes for example...

The cave? It makes sense at some point. The philosopher is the one who sees the "true truth" and tries to share this knowledge, communicate it to the people, by returning to set the rest of the prisoners free. (We were taught the Cave at high school)

And actually I was just wondering how the world would be if all of a sudden we were all "free" of our frames, our chains, those of education, society, personal experiences. They all make us perceive reality in very specific ways... I guess everything would be, I don't know how they would be. You're right. I think it's hard even to try speculate. :)