There are lots of details left to hammer out. This is like an announcement that there will be a committee to commission a study to hire a contractor to change a light bulb. The process will likely take a while and may not complete at all.
Oh? Do you know details on how it's going to work? All I can find is the BRICS Pay site with a very high level overview. They're talking a big game, but as of now all that seems to be public is just talk.
Every indication that it's going to work in style of Bancor, and it's not a difficult thing to implement. It's also very obvious that there is a huge incentive to create an alternative to SWIFT now with US being belligerent towards all the major countries that form BRICS. If you don't understand that BRICS will have its own system of settlement in short order then you're going to be in for quite the surprise.