You must install Firmata on your microcontroller before you can connect to it using Gobot. You can do this in many cases using Gort (http://gort.io).
In other words, you're not programming the Arduino with GO, you're writing a GO program on the host pc and communicating with the Arduino running a special sketch that's designed to let the Arduino interact with host programs ("Firmata")
From: Smaller Go 1.7 binaries - The Go Programming Language
Go was designed for writing servers.
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The canonical hello world program goes from 2.3MB to 1.6MB
Based on those statements, I would say that it is extremely unlikely that GO will ever run directly on an Arduino...