What data are you basing this statement on? I'm genuinely curious because the vast majority of indicators I've seen clearly show that Java is by far the #1 enterprise language. Greenfield projects are probably far more likely to choose .Net but for now, there is a hell of a lot more important legacy Java code that will never be practical to port.

I believe that C#/F# are the future of managed enterprise languages (Roslyn, CoreCLR/FX, and quite soon RyuJIT are far superior to Java equivalents, imo) but I highly doubt their adoption is anywhere near Java.