Yip Man, in his written history, related that Wing Chun derived from the Henan Shaolin nun, Ng Mui (though the system itself was evolved in Liangshan, on the Sichuan/Yunan border).
Sum Nung, in his oral account, related that Wing Chun derived from the Shaolin Buddhist nun, Ng Mui (though the system itself was evolved by the monk, Mui Shun, in (Guangxi?).
The Cho family, in their written history, related that Wing Chun derived from the Shaolin Buddhist nun, Ng Mui (though the system itself was evolved by the monk, Mui Shun, in (Guangxi?).
Thus we have 3 established branches, two of which split apart in the late 1800s, and the other which split apart in the mid/late 1800s, which chart themselves back, at least in derivation, to Shaolin, or Henan Shaolin proper.
Is this proof Wing Chun came from Shaolin? No. Is it part of a much larger work with information is carefully assessed in a professional and honest manner, without preconception or bias or vested self-interest? Yes.
What else needs to be assessed? Does WCK generate power like Henan, Shaolin systems? Are there artifacts of Henan, Shaolin movements and choreography in WCK? Does WCK use terminology which is found in Henan, Shaolin systems? During the large National Wushu Survey, were any systems found in or around Henan, Shaolin which closely matched WCK in methodology, choreography, nomenclature, etc.? Was WCK, or anything similar to WCK, included in the Shaolin Encyclopedia produced in the late 1990s? Do any of the known and authenticated Shaolin manuals have anything similar to WCK in them?
Check out Ancestors of Tai Chi for a good example of presenting possible historic links.