Wiaan Mulder has been excluded from the Proteas squad.
Shamsi was impressive with the cherry at the Wanderers.
His replacement and the new captain is yet to be named.
"I thought his wicketkeeping has been outstanding."
The cricketer-turned-commentator opined that the failure of batsmen created more pressure.
A total of 13 wickets went down on the second day at the Wanderers.
In the post-tea session, South Africa lost seven wickets for a mere 36 runs.
The leggie was ruled out of the third Test at the Wanderers.
Pakistan have only played three Tests at this ground and have lost two of them.
Faf du Plessis won't play the third Test in Johannesburg.