Wonhyo never continued on to China. He returned to Korea, gave up being a monk, and taught royalty and the common folk as Buddhist layman. To this day, his writings are studied and he is probably one of the most famous figures in Korean Buddhism. His effect is felt even within the Korean martial arts, where multiple systems draw inspiration from his teachings. When I was studying Cheolryun Gwonbeop, we had a mantra that was a sort of martial equivalent of his cave experience, "心身一如, 拳禪一如". Body and Mind as one, Fist and meditation as one."
It's easy to read the story of Wonhyo and think to ourselves that we get it, but have we actually looked deeply into this? What is "oneness"?
Bodhidharma said in the Bloodstream Sutra,
People who don't see their nature and imagine they can practice thoughtlessness all the time are liars and fools. They fall into endless space. They are like drunkards. They can't tell good from evil. If you intend to cultivate such a practice, you have to see your nature before you can put an end to rational thought. To attain enlightenment without seeing your nature is impossible.