There is some concern that the Chinese military is chafing at the bits, anxious to fan Chinese nationalism over Korea and Taiwan. For the generation now stepping down, this is a warning that the US should not be underestimated, and that it would be foolish to think that the US is either near collapse, or is completely unable to recover from its current challenges.
The situation is very similar to pre-WWI Germany, when a rapidly industrializing Germany felt that its path to global leadership was blocked by Great Britain. The Germans saw Britain as a great power in decline; their over-confidence set the stage for confrontation, first with Britain and France, then with the US. Now, China is occupying the same role Germany did, and the dangers and opportunities are largely the same.
In this context, this article is a warning from the older generation to the younger generation that the US's power is still great, and will last for another 20 years. The message is that direct confrontation with the US within this timeframe would be disastrous for China because the US is still a leader in many key areas, and has the capability to revive.