I get what you are saying, but a new stadium is not a weekend thing.
It's restaurants, gyms, offices, hundreds of jobs, concerts, maybe a smaller comedy/small show venue.
It would be a 2nd (much grander) NIA.
It's also thousands of people using surrounding pubs, public transport, going shopping after, using hotels, etc etc.
It's exactly what a big city needs.
I don't think it will happen, but it might be a boost that the city needs.