What if the stuff you want is too small to break out into separate service? e.g. some little util library or even a something like a driver
Also if you use a lot of libraries / apps from a specific language, doesn't it make more sense just to transition to that language instead, or does what .NET buy your team worth it to stay?
If you find yourself using primarily Java (nothing wrong with that, really), then just go all the way. I think the same is true for most any language. It's also valid to start doing everything new in a new language and gradually migrate away from where you started.
Also if you use a lot of libraries / apps from a specific language, doesn't it make more sense just to transition to that language instead, or does what .NET buy your team worth it to stay?