Over the last 20 years, the share of developing countries trade over total world trade increased from less than 20% to 30% (bars). This rise in trade could mean developing countries are ever more dependent on rich countries for their trade, but the following points show the exact opposite is happening.
Rich countries are becoming less important for the developing ones, as the latter are trading more with each other (in relative terms). Today, 40% of their imports are coming from other developing, up from 18% in 1990. Finally, the total value of South-to-South trade, which accounted for 2.5% of world trade in 1990, is now worth 13%.
The "multipolar world" is not going to happen. It is already here.