that is a difficult question. and i dont think we can answer it until we have the extra to try.
we currently have a 40,000 seater stadium, where we average around 36,000 attendance in current times. we currently have 10% obstructed views, take them away and we are left with a full house. is that because we can sell all the good seats every week? or because we can only get 36,000 to turn up for most games? i dont think we will know the answer until we have the extra seats.
you can try polling the fans and ask will they buy a ticket, but them sort of polls even the arm chair fan goes every match home and away.
my humble opinion is phased redevelopment/expansion. rebuild the park end, aim for 45,000 with the obstructed views in the other stands. see how we go, if we are selling out all the good seats expand a little with the redevelopment of bullens road, may 48,000. then again with gwladys, probably to the same sort of capacity but maybe we would get better sales due to no obstructions. then if we are selling out the 3 new stands, construction of the main stand is the make or break for how big we can take it. if we arent filling up just go to 50,000 with no obstructions anywhere, if we are filling up try to get as close to 60,000 as possible. obviously figures are just pulled out of the air but im sure you get my drift. non commital to anything more than the next development. thats how goodison park was built in the first place. it might take ten years, but if they get it right it would be worth it.