I don't know if any of you were aware but there has been a diagram of this building up for some time now in SF's diagram page:
http://skyscraperpage.com/diagrams/?cityID=114
(second to left, next to Transbay)
This image also shows how these new proposals will break out of the tabletop.
Thinking about how much 555 Cal sticks out like a thumb, imagine having 5 high rises of it's size or taller on the skyline and how much that will improve the overall bulk and height.