RC is the only part of BRICS that is likely to compete with the top 7 democrat nations. India will likely be asked to enter the G7. Their only issue is that they are still too friendly with Russia. But they are a democracy. And they are a growing economy that is already larger than some in the G7 now.
South Africa is not even really in the BRICS anymore. They are not going to be any better than Uganda or the Congo in a few years. And in many ways they are worse.
Brazil is just a minor league player. They are not politically stable. And they are not economically stable. So, outside of selling off the rain forest, they are not world players. G20 will be their home for decades if not centuries.
The combined GDP of BRICS is higher than that of G7.
Lived in Brazil from 2012-2014. Second largest economy in the Western Hemisphere, but they can never be a global player with the clown world politics that makes ours look like a Platonic Republic.