Really? Where are the Go versions of Spring, JEE, Android, Solr, Liferay, Kafka, Gemalto, microEJ, PTC, Aicas, Ricoh, Kyocera, Java Card, VisualVM, JFR, JMX and plenty of other stuff I haven't bothered to type?
Seeing how .Net is being sold to enterprises without such libraries I would say that they exist because business happily buys into any promise that something increases productivity even if that is just salesmen's lies. But it requires good salesmen not good engineers.
Why Java devs automatically assume that every new language is made to overthrow Java/C#? They might still to provide better development in a particular domain. Go or Python or JacaScript are good at rivaling Java at mainstream language, and so what?
A language feature alone doesn't replace an ecosystem with 25 years of production experience across platforms that aren't even supported by Go.
After getting generics, Go still needs to offer JFR/JMX/VisualVM like monitoring and dynamic code loading capabilities (Go plugins are very limited), JEE/Spring like Web tooling, Liferay/AEM/Magnolia like CMSs, an OS of its own and real time GC, card chips, M2M hardware gateways, printer enterprise configuration appps, and plenty of other use cases that many on HN seem unaware of its existence in enterprise scenarios.