Sure, multiple growth poles are a safety-net for the whole world, but to expect EMEs, by themselves, to lift global growth to former levels will be unrealistic. Note that EMDCs account for less than half of world GDP even when measured at PPP valuations, and only about a third of the world trade in goods and services.
The second question about EMEs in the global context relates to decoupling. The decoupling hypothesis held that even if advanced economies went into a downturn, EMEs would not be affected because of their improved macroeconomic management, robust external reserves and resilient financial sectors. The crisis failed to validate the decoupling hypothesis as all EMEs were affected, admittedly to different extents.