The future of the religious form of marriage is in the hands of the respective clerics and faithful people.
The future of civil marriage is to be placed away from the hands of the State, until it lasts. And for civil wedding to be eliminated.
What is the State for, in fact, but to manage conflict situations also within its own society?
If I establish a friendship with a neighbour, do I have to make that public in the Town Hall? Of course not. But if I start an argument with them, it may go as bad as to warrant the intervention of the Law (the Police, or even “just” a lawsuit).
And so it should and surely will be that there will be no hand at all of the State when two people want to live together: whilst the weakest component of the couple, if the love and friendship disappear, will only have to demonstrate the two were living “as husband and wife” (in Ancient Rome, more uxorio), for the Law to act in their defense.
Even if policies dictate incentives for couples, again all they should have to show is that they are a couple (perhaps, a stable couple in the second year of cohabitation)…how it all started, and if there was a ceremony with a mayoral representative mimicking the religious ritual, all that must surely be immaterial from the point of view of the individual’s rights.
The above will finally re-align legality and societal mores, now so completely at odds with each other. With the added bonus of further separating God and Mammon, as Somebody recommended to do a few years ago…