"Life normally evolves in nature in balance with everything around it, with nature providing the careful checks and balances to keep harmony"
Actually, no. Life evolves specifically NOT in balance with everything around it. The reason mutations succeed and creatures evolve is that they have broken the harmony in a way that is to their advantage. That is, they can now overcome the previous checks and balances. If artificial cells - or artificial intelligence - wipes us out, you can think of it as evolution in action.