An opportunity lost by the looks of it.... the stated intention is "in support of efforts to decrease carbon emissions and congestion on the roads". Banning of ICE cars (internal combustion engines) would achieve the carbon emission aim, whilst boosting more ownership of electric vehicles which spills over into lower emissions overall outside of the zone too.
South Africa has no incentives at all for EV ownership apart from the carbon tax on purchase not being paid (but the tax is very low compared to elsewhere).
The answer to congestion is a reliable, safe, clean and timeous public transport system. Instead of banning cars first, let's get the public transport sorted out so that people want to use public transport.