Not by USA or other allies. However, the Taiwan military could make it painful for the mainlanders. Or, the right bribes to the right officers might grease the skids.
However, this is thinking like American leadership: too short-term. What happens the day after China controls Taiwan? Do all Taiwanese meekly submit to their bullshit? Or do they become an extreme version of Hong Kong? It's mostly Han in Taiwan, so the depravities seen in Xinjiang and Tibet couldn't be instituted there without jeopardizing the legitimacy of the entire state. As long as Chinese leadership is fairly secure in their positions, they won't invade Taiwan.
