These days .Net applications are fully self-contained, cross-platform, with everything you need in the bin. Unlikely Microsoft could go after people similarly even if they wanted to.
I definitely feel bad for Java developers, Oracle has ruined Java's reputation and made companies more careful around it even if they may not be impacted.
As a Java developer, I am certainly much happier now than I was 15 years ago when Sun couldn't invest more in Java development.
Disclaimer: I work for Oracle, but not on Java/JVM.
The JDK is under the same GPL 2.0 license as Linux, which is a rock solid way to ensure nobody can ever make it less open source. Several big players are contributing to Java and due to it being GPL licensed everything is open source.
For the .NET ecosystem it's still 99% Microsoft with virtually no others contributing. And it's only MIT licensed so anybody picking it up in the future can do so without contributing back to open source.