[nem-en] ManagerClass.Instance == pain!

[vc]

> On the other hand we could introduce some more utility macros to
> simplify the transition.

Yes! :) 
In true macros is fine. 

> Like module from my example would become
> instance class marked with ManagerAccess macro and having Manager
> passes in its newly introduced constructor... Anyways I expect it
> could still be very irritating for users to face such big design / API
> change.

You should think about future users. Language is not released yet.