> Loadable modules like the way Apache/nginx do, or 
    > Nagios or quite a few other basic infrastructure 
    > applications.

I agree this style of composition is not currently possible in Go, but I do not agree that it is necessarily a good (in the engineering sense) solution to the requirement(s) it solves. There are lots of other ways to communicate between dynamically dispatched blocks of code, and dynamic code loading is by any account fragile.

Or, to put it another way,

    > you can't expose your Go code through any kind of 
    > native interface

I'm not convinced this restriction is anything but good.