It doesn't have to be China. There are far smaller countries in Europe that are perfectly viable, and even countries that aren't viable, like North Korea, can still continue to exist despite that.

In this case, it's good that it happened so fast. It could have gone a lot worse.

Hardly any state in Europe can afford full self-sufficiency in isolation without enormous suffering.

North Korea (with more population than DDR) survived Soviet collapse but just barely, losing hundreds of thousands in a protracted famine, until landing on client relationship with China. Not a realistic scenario for East Germany.