The main stumbling block to planning consent for a bigger capacity seems to be transport infrastructure. If that is the case, why hasn't the upgrade of the freight line from Kirkdale to Edge Hill been suggested - its the dotted line on the map that starts at Kirkdale and crosses County Road, Walton Hall Avenue, Utting Avenue, Townsend Lane, West Derby Road, Prescot Road and Edge Lane before reaching Edge Hill.
If there were stations at each of the above main roads, most people from out of town would be better off parking up there than driving into Anfield. Nearly everyone from town would have an easy rail link to the ground, with it joining up to both the city line and northern line. Parking problem cut in one go.
In terms of regeneration benefits, linking the whole of north Liverpool to the rail network would be a massive boost and local people given proper access to jobs in the the land of plenty that's been promised for Wavertree. The traffice burden on the main roads that the line cuts accross would be eased and given the line's already there, it probably miles easier than the ill-fated tram proposal to get off the ground. Even if the tram eventually happens, it'll link in with this line.
So there yiz have it: Uncle Retro's expanded the ground and regenerated north Liverpool in one go - piece of piss.