One China policy was never just an appeasement policy towards China. Because One China policy itself has a lot of ambiguity. This one China could be both ways, since the US has never formally reject and institutionally prevent the possibility that ROC could ever "retake mainland". The only reason this does not seem possible is because the PRC has performed extremely well in governing and controlling the mainland, which makes ROC's comeback very unlikely.
The ROC will always remain a potent phantom that will haunt the PRC. Because it is a significant part of contemporary Chinese history. And it is the ultimate asymmetrical weapon the little island of Taiwan has that can offer an offensive capability on a strategic level. Without this specter of a resurgent ROC vowing to re-take mainland, the island of Taiwan will be purely on the defensive posture, without the possibility of staging an effective offense. This would mean that the PRC would have lost the most effective challenge to its own legitimacy in mainland. This will shift the play ground all into Taiwan island. The outcome of this will be a pure arms race between two side with one side outclassing the other in every aspect.
