The decline affects health sciences, natural sciences and engineering. In fact, it affects health sciences the most, because there is virtually nothing in that field. In natural sciences and engineering, there are still a few bilingual journals, but that is all. It is really in those fields that there has been a major loss.
I think you raised an interesting point when you mentioned the revision of the Official Languages Act. That may be an opportunity to insist that research have strong roots and take its rightful place.