Maybe so. But you yourself have admitted that Wing Chun may have evolved from one of the southern village arts. Ben Judkins seems to suggest the same thing in his blog. These southern systems all have similarities. Like I've pointed out, we have about 150 years of divergent development to explain differences.
Why would you assume the same Southern village art as a starting point for all? Why assume crossover between Hakka and non-Hakka?
As you know my theory is that wing chun is based on pole, while others are not. I have reasons for saying this.
Who knows what that original southern village art was? An older form of White Crane? An older form of Hakka art? All speculation at this point. But given convergent legends and historical hints, an older version of White Crane would seem to be as likely a candidate as anything.
White Crane is a sanchin system. This means that it works in a completely different way to the way that wing chun works. No reason to insert it into wing chun history.