This is as good or better a theory than anything I've seen posted by certain "researchers" who frequent these forums. Essentially it is what I tell my students. Namely that before the era of Leung Jan, nothing is certain. There is the instructive "legendary history" of Ng Mui and Yim Wing Chun, and the more plausible, if less romantic "probable history" which remains somewhat speculative due to the paucity of factual evidence.
IMO the "probable history" is that Wing Chun
began as a southern offshoot of Yongchun Bai He, with influences from other southern short-bridge systems such as the Hakka methods. But since the time of Leung Jan, WC has developed a unique character to become a very distinct group of systems. As I practice a branch of the Yip Man lineage, I also emphasize the contributions made by this great grandmaster, as well as the distinct flavor of my old sifu's "WT" branch.
Anyway, it's reassuring to hear that an individual who actually has experience in Crane Boxing shares this view.
Another thing... Since Okinawan Te also has roots in Chinese crane boxing, and Te gave rise to Japanese Karate, which in turn provide the core of TKD, most of us are distant cousins in the same family. Maybe that's why we all bicker so much???