1. Node.js was abandoned and replaced with io.js.
2. Io.js was relabelled as node.js.
3. The node.js project was put under open governance via the creation of the Node Foundation.
This doesn't really compare to npm:
* The npm-cli's name is using npm Inc's trademark: giving it away would leave the company with no name or create unwanted ambiguity between npm Inc the company and npm-cli the (then) community-owned open source project unaffiliated with the company.
* Yarn does not share any source code directly with npm-cli, it's a complete reimplementation of a similar feature set. It's currently backed by a mirror of the npm registry but that's the extent of the overlap.
* The Node Foundation already exists and Yarn is already owned by the community. I could see Yarn joining the Node Foundation and the Node Foundation replacing its bundled dependency on the commercially owned npm-cli but even then npm Inc has nothing to contribute to the process.
Personally I would much rather see Yarn join the JavaScript Foundation because it speaks to the broader appeal of Yarn outside the traditional "Node community" and the politics involved in the latter and its close ties to npm Inc.
FWIW I consider the close ties between the Node project and npm Inc nothing more than a historical accident that has resulted in a conflict of interest that is overdue to be resolved by dropping npm-cli from the official releases.
Now that yarn is no longer distributed using npm (although it's still possible to install it that way) that seems more realistic than ever.