Sorry, misread your intentions there a little with the natural true state and Yin Yang part of your post, because I thought you meant the Legion was going to leave something to be in a natural state. The natural state of the universe is balance, chaos is the natural state of the Nether. (Balance not meaning all encompassing peace here.)
My post was particularly not about balance, but about the intended eradication of everything by way of Fel from Sargeras. With his new plan that we found out in Legion even being a supreme Fel-Titan Pantheon to make it happen, so specifically not without Titans, but only Titans left to bring about his vision of the universe.