The first fork drove some away because some felt the ecosystem was fragmenting but many came back after they merged back or understood io.js advantages. Some new developers who might have choosen the language never came back. The growth curve was altered because of those events.
This new split will not drive people away or stop the adoption in the same way. It's may cause some to put there changes in this new fork but this new fork will push changes to the node.js repo and this new fork will keep pulling changes from node.js.
