Two posts well worthwhile reading:
a) Val Shawross, local London Assembly member, on the subject
b) potential for two-way working not shown in TfL's options.
Ironically, by removing the gyratory to make Vauxhall more pleasant for pedestrians and cyclists, traffic volume (which must include trips made on foot or by bike) is likely to increase rathet than decrease!
Impossible shout the TfL traffic engineers. But the reality of making a place nicer to wander and cycle around is that more people will make journeys there - just look at the southbank before the London Eye and after. Of course, the engineers may prefer loads of polluting motor traffic over people ambling kind of traffic. Do we really want a motorway style no-mans land to remain in central London, between vibrant Waterloo and the buzzy new US Embassy and Battersea Power Station area?