Why do you think so? Microsoft has good developer tools of their own, Google is already building Android Studio on the IntelliJ platform without owning the company. Making IDE's is neither company's core business. I'm sure Jetbrains is a healthy business, but for Google or MS it's peanuts. I don't see the benefit of them owning Jetbrains, whereas on the contrary it would be good for Jetbrains to stay neutral.
Resharper and Jetbrain's other .net tools may be enough of a reason, would be a nice add to VS. Also, MS is clearly showing an interest in Linux ATM and I doubt VS is going cross platform anytime soon, and they know the value of good developer tools.
Google makes a logical partner for JB. IntelliJ is already the foundation of Android Studio and Kotlin could be a replacement for Java on Android.
Facebook uses its toolset. That's who I'm hoping for! But secretly, JB's stewardship of the developer perspective is worthy of independence.
I hope not, I don't want to see developer tools come down to a choice of Apple, Microsoft or Google.
This is wild speculation at best. If anything, Jetbrains seem to be extremely resistant to being absorbed by larger entities.
If Google acquires Jetbrains, Kotlin winds up being a first class Android citizen, I think.