They just need some low line defense. I and most other BJJ guys I know have nothing but respect for MT guys because we've eaten our share of knees during the takedown. I think the basic principles of WC could be used to defend the takedown but they simply need to add the techniques and practice them. MMA style grappling is either new or rediscovered technology depending on how you look at it and WC was simply not designed with it in mind.
Originally posted by WingChun Lawyer
"As far as I know, there are no anti takedown techniques in wing chun, except having a strong base and hitting the other guy desperately with your elbow.