Well I imagine much of the "concern" around removing cars from higher density areas like the CBD etc is how will goods/supplies be brought in.
Using the tram network seems like a potentially nice solution. You'd have to make sure the loading and unloading steps don't take up too much time and clog the network, but I can imagine that there'd be solutions for that such as loading in spots off of the main network and unloading well prepared batches that then get wheeled off to their close-by destinations.
Plus, if you go all the way on removing cars in certain areas, increased tram through put might be plausible.