I'm not sure if anyone who knows what they're talking thought China was going to fail in 1990. I think most of the world at that time was concentrating on Japan, Russia, and US. China was too small of a player to be noticed by anyone prominent.
In any case, my observation is based on numbers and trends. Ebbs and flows for a country, government and culture. Debts and growth. Demographics, core strengths, and relationships. I stand by my observation: China will most likely fail.