Having a new open source Js engine is great, with ChakraCore, Microsoft is reconnecting with the open source world, and that is a very good news.
But to be more focused on the Node.js engine, v8 have been around for a very long time, it is mature, performant and stable as we all know.
However, it comes shipped with great ideas for Windows based IOT as @sandeep said, and may have some useful features that are not in v8 core. It is a great news since it is bringing a new vision into Node, I think it is essential to keep improving it, experimenting, sometimes out of our rock solid basis. This way we can extract some ideas that are worth implementing, and enhance the whole platform.
Having an open mind leads more often to enhancement than a closed one.
"Copy the best, invent the rest"
Keep in mind that I do not say, replace v8 for ChakraCore for the next Node major. I just say that if they made a pull request, it is to add features, so it is worth for the community to take a look at it.
I don't mean to offend anyone here, so if someone is feeling offended, you have my deepest apologies.