Whilst I think he highlights an important data-point, I don't entirely agree with Michael Turton's analysis of the out-come of a recent poll showing that only 52.3% of KMT supporters believe that both Taiwan and the Chinese mainland belong to "One China" here. Unifying Taiwan with the Chinese mainland is not really the KMT's "core mission". It has always been more of a unifying credo, an identity similar to the UK Labour Party's Clause 4, something which a core can rally around without necessarily believing it will be implemented any time soon or even ever.
Why do I think this? Well, asides from all the other reasons (like, for example, the fact it hasn't happened yet), if it was the "core mission", then it would be pretty strange for so many KMT supporters not to actually support it. The KMT vote is more the product of ancestry, belief in certain (fairly statist in places) economic policies, and networks of patronage that may stretch into some dark corners, than wholesale commitment to Chinese nationalist (small 'n') ideology and goals.