Does Microsoft adopt Chromium/Blink for embedding in UWP apps and Electron? That will reduce memory and storage requirements for the latter, but greatly increases the attack surface of the former.
Microsoft is also taking on an _enormous_ maintenance burden in integrating it with their own sandboxing and protection mechanisms. I'm in disbelief that the ongoing cost of maintaining this fork and tying themselves to Chromium will be worth it.
And the incentive for Google to now embed more and more ChromeOS/mobile device management into Chromium. For example: Google intends to ship an alternative credential provider for Windows 10 through Chrome. Microsoft will have to painstakingly isolate every feature like that which Google adds, and adopt an aggressive posture of doing code reviews of Chromium.
I'm not sure how, given that they are such strong competitors/adversaries, this can work out.