Perhaps they'll help get it working as-is, then help with a project to make the framework more engine agnostic, then move over to using theirs instead of V8.
The cynic would suggest that "extinguish" comes next, though I can't see that working for them in this case in this day so maybe they'll be sensible/good enough not to try that one...
On MS's past form, I doubt they will cede server-side JS to Google's engine permanently. They have money to throw at people to throw at making their engine and node work together, if they so desire.
What worries me is that lots of Node.js code may get developed on Windows and be unable to run on other implementations. I have seen Windows-only Java code. I know it can be done.
And it always seems a waste, for it already should run fine under Cygwin, much closer to the original implementation.