Interesting, I haven't heard of Valhalla (I haven't really used Java since around 2014). From their landing page it seems like their priorities are value types (which Go already has - you need to specify pointer types explicitly) and support value types as generic type parameters, which Go has to do, because it has value types.

I guess it will complicate things a bit, you're right. I'm pretty happy I don't have to use Java anymore though :)