Drupal Core and Modules

The main question about any future implementations in order to achieve a truly multilingual Drupal is how much -limited- support should be built in into the core, how much in core modules, and how much can be provided by contrib modules.

My premise here will be *Let's not have in the core things that don't need to be there*. Ideally, as I see it, there should be some limited support in Drupal core, then some functionality that can be enabled as a core module, and then some contrib modules providing specific features, but that don't need to patch the core because we already have some language-oriented pluggable support already built in into Drupal.

While it may seem that any part of the functionality may be implemented either as a core module or as a contrib module indistinctly,  the distinction between 'core modules' and 'contrib modules' is actually crucial because of the policy of 'not having specific functions in Drupal core for calling non core modules', which anyway is a good policy  IMHO.