I've had seasons tickets for 33 years, which I took over from my grandparents who had them since 54'. I've seen the ebb and flow of the fans first hand so it's not like I'm just speculating here.
I was in empire, and I got to pick my seats in BC Place when the place was half built, before the roof was even made. I'm one of not too many people besides the builders that have been in BC Place with no roof on it.
The move to BC Place didn't fill the stands. The first few games reached close to 50k, and averaged 45k that year, but have never sold out a regular season game if my memory is correct.
I'm sure more people will come, but not 25-30k more which is what we would need to sell the place out.