I though the whole point of io.js was that they would work on the project faster than Node, but eventually merge back into Node once Joyent became more transparent. The Node release cycle was pretty slow and they had some dispute with the contributors (top 5 original Node contributors now working on io.js)
They publicly stated they will merge back in upstream eventually all being well. They're doing it for the good of Node.js, not to create a rift and divide the community's efforts.
IIRC the Node Forward initiative was more explicitly focussed on merging back than io.js is. The subtext of io.js seems to be "we'll move forward with or without Node moving foward with us".