Pie and sky come to mind, but never in my time so I won't know if I'm wrong!
The scour on the outside of the barrier would mean the upstream channel would move to the north side, and New Holland, Barton and Barrow would silt up or have very little water.
The huge bell-mouth created for KG access would have no natural flow and would silt up without very constant dredging. All the frontage inside it would still need flood protection. Why not go the whole hog and have one large new lock?
Commuters coming in from the west would be tempted to use the new road and then clog up the access back into the city centre, adding to existing traffic from the east and the docks.
What is the shopping trolley capacity of the Lagoon?
Otherwise it looks really good .....