LOL... they were not able to replace the players, because all of them have migrated to other countries such as England, New Zealand, Australia. Some have even decided to represent the smaller nations such as Netherlands (Roelof van der Merwe, Wesley Barresi, Stephan Myburgh). Even those who stayed behind in South Africa, such as Dale Steyn have been given a raw deal by the team management.
The case with Pakistan is different. Despite the low salaries, the players are not migrating to the other countries. Well... a very few such as Fawad Ahmed and Imran Tahir have done that, but such cases are more of an exception rather than a norm. Pakistan still remains as one of the best teams in the T20 format and their player pool is producing a lot of promising players every year.