Thats why its important, the US stays ahead of the curve
The reality is that power remains the principal safeguard against war. To draw from Henry Kissinger, there is no historic evidence that "peace is the normal condition among states." While democracy, international law, treaties, relationships, etc., can mitigate the risk of war, they cannot completely substitute for a lack of sufficient power when critical national interests clash. China keenly understands the importance of the balance of power. U.S. policy makers would do well to do the same, as the world is not an idealistic place nor is it unipolar.
Having said all that, I don't believe war is the most likely outcome even as China gains power. At present, a Sino-U.S. war would inflict substantial damage on both parties (even excluding a nuclear exchange). The benefits don't outweigh the costs for either side. Power realities promote deterrence of conflict. Nonetheless, there are some critical differences in interests e.g., Taiwan. There is common agreement in favor of a unified China by peaceful means. But should China seek to pursue unity through force, the rules could change. One could argue that the U.S. would ultimately blink and step aside from such a conflict. But doing so would imperil critical U.S. interests ranging from relationships with major trading partners i.e., Japan and South Korea, that would be demoralized by U.S. abdication, to open passage in vital shipping lanes. Under such a scenario, one could reasonably expect renewed arms races in East Asia and likely greater instability as U.S. abdication would create a dangerous power vacuum. Hence, my guess is that risky as a military operation would be, the U.S. would intervene in the case of a China-Taiwan conflict unless Taiwan acted to provoke the conflict e.g., by openly asserting its independence.
We are also becoming rivals for the same resource, oil. The world isn't close to running out of oil, so the price of oil hasn't gone up because of low supply, rather its higher demand. That and the fact that we haven't built a new oil refinery in 30 years.
That's another future faultline. In a future where resource scarcity is one plausible scenario, resource nationalism could assert itself. China's growing navy reflects China's desire to assure reliable access to natural resources, especially oil. China's relationship with Iran also reflects such dependence, as well.
Already, there were reports that China had simply halted shipments of rare earth minerals to Japan to extract the release of a Chinese ship captain. China initially refused to comment (confirmation would have triggered a trade dispute at the WTO) and later denied any policy change. That allowed China to exert leverage and avoid a trade war. China, in other words, is a keen practioner of power politics.
Finally, one has to understand that China's desire to strengthen itself is also a function of a long, tortured past that saw alternating periods of power and weakness, sometimes destructive fragmentation and instability. China very much craves stability and is seeking to translate its growing economic power into the broader means of assuring itself the kind of stability that had proved all too fleeting in its past.