Just had a look to the squads of both teams and it seems like South Africa a pretty thin on their batting. Seems like they are pretty much reliant on Elgar, van der Dussen & QDK. There are exciting prospects like Kyle Verreynne & Keegan Petersen, but they haven't quite delivered in their limited opportunities. And to throw them against the likes of Bumrah, Shami, Ashwin, etc. is going to make it incredibly tough for them. This series is going to be an ideal time for Markram to switch against a worthy opposition as he hasn't quite delivered against a stronger side in his career barring Australia which was almost 4 years ago!
Even though India has a very good bowling attack they are no competition to the likes of Rabada, Ngidi, Olivier and Mulder who are going to tear apart the Indian batting line-up provided a little bit of help from the surface. I was quite surprised when I came to know about the fact that Duanne Olivier have got over 500 wickets in First-Class Cricket. I would say the Proteas still needs to use him sparingly and give him a role similar to that of Colin de Grandhomme. India were under the pump if they had to face Anrich Nortje. South Africa's bowling attack almost nullifies their weak batting and infact gives them a chance over the Indian team.
India would need about 320 runs to compete. For the surfaces, I don't think they would be as difficult to score as they were in 2018 series. India's middle order has to be a little more stable as far as their performances are concerned.
Also I am trying to look at South Africa's probable playing XI from my POV,
Aiden Markram
Dean Elgara
Keegan Petersen
Rassie van der Dussen
Temba Bavuma
Quinton de Kock
Wiaan Mulder
Keshav Maharaj
Duanne Olivier
Kagiso Rabada
Lungi Ngidi
Perhaps Verreynne can be Petersen's replacement?