I'm sure it has, but in the meantime Java is making great strides as well on multiple important fronts -- low-latency GCs, a next-gen JIT, AOT compilation, native ffi, low-overhead in-production profiling and lightweight concurrency, and the main problem with Microsoft's technologies remains that they break compatibility every five-six years or so. Now it's .NET Core, and it wouldn't be a bad bet to guess that in five years it will be something else. We're at a point where it's so hard to make changes with a big bottom-line impact (arguably there weren't too many such advances in the past twenty years) that very few actually justify breaking compatibility, and companies know that. So while smaller software can afford switching from one technology to the other, big "important" stuff requires a compatibility lifespan of at least ten if not fifteen years, something that Microsoft has never been good at. It's possible that with their focus shifting more to the backend with their cloud offering that would change, but it appears that their cloud strategy is to support all software platforms rather than focus on their own. That's why we see Microsoft now hiring engineers, as well as getting some CLR engineers, to contribute to Oracle's OpenJDK [1].
[1]: https://mail.openjdk.java.net/pipermail/discuss/2019-October...