Future Rail Network Expansion plans?

I've been wondering if there are any plans for a rail network upgrade / expansion in SA

I've recently moved to JHB and seen the potential of the Gautrain. Why can't this be implemented in other big Cities acorss the country like CPT & DBN with high speed rail connecting them all together?

The one thing that SA lacks is a good public transport infrastructure - why can't we have trams, subways HSR and an interconnected transport systems like in developed nations? I don't think it's that far put of reach for us to build.

Are there any plans to get something like this built in the next couple of decades? Or are hubs like the Gautrain just a novelty?