To those with limited rights, it is not a matter of 'fixing' the definition of civil partnerships to resolve "duties and responsibilities". It is a matter of being able to just ....go get married freely as others do ... whereupon those "duties and responsibilities" become just one aspect of the relationship.
They want marriage to be a formal, **sometimes** religious, recognition, by the state AND/OR their church, of a deep personal commitment... just as it is for heterosexual couples.

   You may think that it is just nitpicking detail.. but most folks who want a 'marriage' want it to be equal to anyone else's. The words used.. 'wife, husband, bride, groom, partner, spouse' should be a matter for them to decide on.

For that matter, I think it should be **legal** for any combination of people to 'marry', as long as they are of legal age. More complex relationships than "two partners" would have to submit carefully approved (by a court) documents detailing how to handle situations not covered by traditional one-to-one marriages.
No, I do NOT think this is likely soon... maybe in 100 years.