As long as de Kock was there, South Africa had a chance of setting up a respectable total and even a distant chance of avoiding the follow on. But since he is gone, I think that now a follow on, and later an innings defeat looks like a surety for South Africa. Senuran Muthusamy batted well during the first test. Let's see how good he is in the second test.
Even if de Kock was still playing, he would never be able to set a decent total without support from 2 other players. Jadeja already removed Muthusamy and this is not exactly surprising since he is not exactly a batsman to begin with.
Right now South Africa is trailing by 418. If India could add another 200 runs, then they can set a target of 600 plus for South Africa. And the bowlers will be having two days to bowl them out.
In my opinion, India probably might not need to bat since all of their bowlers(Seam and spinners) are performing brilliantly and it is only a matter of time for South Africa to probably lose this one by an innings.