Lets start with l10n: I assume you do get new descriptions and updated
ones (english) from our Packages files? In that case there wouldn't be
the input for you anymore, so you couldn't provide us an english
"Translation". My current plan would be that the archive will provide
the english translation file, so you can grab that and do with it
whatever you do today with Packages.
If that does work for you, it will mean in the i18n tree *we* will
provide Translation-en.bz2, you fetch that, you get that back to us in
the normal way. Or somehow like this.
*I* think missing long descs right in the middle of a dist-upgrade is of
small enough impact, especially as we want people to update apt and
friends first in a seperate step anyways and can be dealt with with a
proper paragraph in the release notes, and its not bad enough for us to
have a legacy file around for a year.