Apart from the ROC and PRC, the third option is to make Taiwan legally independent by ending the ROC Constitution (enforced in 1947) in Taiwan, while preventing the PRC (established in 1949) from landing on the Taiwan Province (returned to the ROC in 1945 by Japan).
This is based on the premise that as long as the ROC still rules Taiwan, Taiwan is not independent from the old China (ROC) and hence still subjected to the eventual goal of Chinese unification on the ROC's terms. Moreover, the ROC rule was seen as a transplanted regime originated from mainland China, rather than of locally independent Taiwanese origin.
However, Taiwan is already independent from the new China (PRC) as the PRC never rules Taiwan and hence never achieves Chinese unification on the PRC's terms.
When the ROC was founded in 1912 in mainland China, Taiwan was still under Japanese rule following the result of the First Sino-Japanese War (1895). At the end of the Second Sino-Japanese War (1937-1945), Taiwan and surrounding islands were returned to the ROC. The subsequent Chinese Civil War (1946-1949) resulted in the ROC-PRC split as the ROC was evacuated to Taiwan and the PRC was proclaimed in Beijing in 1949. The ROC retained China's seat in the United Nations until 1971.
The PRC insists that it inherited all the territories of the ROC, including Taiwan but excluding Mongolia and Tannu Uriankhai. The ROC pretends itself as the sole legitimate government of all of China, despite the fact that it now only rules Taiwan and surrounding islands.
It is very hard to explain the conflicting views among 1) ROC, 2) PRC, and 3) Taiwan Independence. While Taiwan officially calls itself the ROC, but the ROC is actually the mortal enemy of Taiwan Independence; this is because both the ROC and PRC are of mainland origin and are aspiring Chinese unification.
>>> My very simple explanation on the international position on China's sovereignty (ROC, PRC, and Taiwan Independence) <<<
