This is...actually a very interesting idea. Like the wizard, it is great and terrible. But interesting. Short summary: new law in Mexico City allows couples to sign a marriage contract with an expiration date (minimum of two years), after which time the couple can choose to extend the marriage or simply let it expire.
My first reaction is amusement, because it seems like an idea got pulled from a speculative fiction short story and turned into an actual policy/social experiment. The stated goal of the policy is to reduce the divorce rate - it will almost certainly be successful at this, even if it does not increase the number of marriages that last to three years or longer - and the contract requires the couple to make many long-term decisions upfront (what to do with any potential kids, etc.), a step which would probably benefit many "traditional" marriages.
Let me get this out of the way: Yes, I just completed one year of marriage. No, I'm not looking to get out, or wishing I had this kind of deal. Just intrigued by the potential social impact the policy could have, especially if it's successful.
To oversimplify, there are three ways this could go:
1. Nothing changes except for the terminology. Marriages still fail at the same rate, with the same amount of fallout, baggage, and legal drama.
2. The Nightmare Scenario. Mexico City replaces Vegas as the hotspot destination for quickie, ill-advised weddings. People enter marriage lightly (because that's not already happening) without taking seriously the long-range implications. Families are devastated, childrens' lives ruined, and we move further down the slippery slope to legally endorsing bestiality, necrophilia, pedophilia, and all the other scary things "pro-family groups" are going to trot out to demonstrate this is an irreversible step towards the Apocalypse.
3. The Best-Case Scenario. I can see an argument for this actually making marriages stronger. I think the big problem with many marriages (and long-term commitments in general) is people don't actually understand what they're getting into. They think it's always going to be the fun, sexy, easy relationship it was at the beginning, and freak out when it becomes work, the "spark" is gone, and they realize they're trapped in the relationship for the rest of their lives. Or, you fall in love, marry someone, then see what they're really keeping behind their mask - whether it's an inability to properly clean the bathroom, a tendency to sleep around, or severe psychopathic tendencies - and realize you need to get out quickly. This starter kit approach to marriage allows people to learn what being married really means and who their partner is in a much more forgiving environment. Taking off this pressure might mean that when the problems come, people feel comfortable working together to resolve them instead of freaking out and running away.
I honestly think in the short-term the first scenario is the most likely, especially since there will likely be so much stigma against a marriage with an expiration date. It will be great or terrible for couples in equal numbers, based on what they bring into the relationship. What I really want to see is what happens if the policy survives long enough for a generation to grow up thinking it's "normal"; then we'll really see something interesting.