Nothing will happen. And Taiwan does not need to declare independence. Taiwan has its own democratic government, has its own president, its own currency and it has the United States. What can your beloved commie China do? Hey commie corsair! I strongly encourage you to accept the reality that Taiwan will never join your oppressive communist regime. Taiwanese people enjoy freedom, and liberty, so why would they want to live under the commie and be subject to commie rules just like Hong Kong?  Common don't be too selfish mate.