400k over thirty years sounds right, that's about 13k/year.
400k/year would mean Surrey becomes larger than New York by 2050.
Anyhoo, at their current growth rate Ladner/Tsawwassen should see
660new residents by 2050; all the growth is in North Delta, which is effectively Surrey.
Surrey City Hall predicts ~70k more South Surrey residents in that time frame, but they're not likely to work in Richmond, and very likely to have a RapidBus to Newton by then.