BRICS will help all these member countries to grow whereas in the Old World Order (ie the unipolar world) they couldn't because US regime prevented them from growing either by sanctions (economic war) or invasion (armed conflict).
With more power poles we go back to a normal world that existed for thousands of years until 1991.
The success of BRICS is unpredictable at this point since during transitional phase when the World Order is changing there is a lot of tension and conflicts. In the chaos, everything is possible. From a smooth transition (with the existing conflicts on small scale) all the way to global nuclear war and extinction of human race.
Only one thing is certain though: the unipolar world is over.