I have been to the delle alpi last year and I think that a problem of the delle alpi ist that there is nothing around the stadium. it is far away from the downtown, there are no shops, reataurants and other things around the stadium. Fans can only come there, watch the game and go home. I think that much more people will come if there are shops, cinemas, restaurants, a juve-museum and a juve-fanshop around the stadium.
People could come earlier, go shopping, eat something and visit the museum. The fans would stay much longer at the delle alpi and spend their money there. I have been to the nou camp a few years ago. there are restaurants around the stadium, a barca-museum and a huge fanshop. the fans come hours before the game starts and spend their time there.
I really think that more fans will come to the new stadium. now the delle alpi is just not a good football stadium and i think that the fans will really enjoy watching games in the new stadium which will be much more comfortable. Ito my mind 45.000 to 50.000 seats would be great.