Brownlie needs a big score here. Nothing less than 50, that's for sure
Would you drop Brownlie if he fails this Test? That'd be harsh imo. He earned at least two more series after his efforts in South Africa.
If you look at his record he's actually done alright for a guy who usually comes in at 9. Needs to work on playing guys above 135kph if he wants to become a genuine allrounder, ala Vettori.