It's general opinion that Rolando Villazon has, with his inability to perform the upcoming production of Elisir at the Met due to vocal troubles, has probably come to an end of his career, or at least his career as a superstar.
I hope this is not true, and I certainly wish him all the best, but even should he rebuild himself and continue, there is nothing more devastating to a singer than the decline or complete loss of their instrument. Regardless of why it happens, regardless of whether it happens to someone who sings at the Met, or someone who sings at the Back-Ass-of-Nowhere Light Opera, it's a tragedy.
As a singer, your voice is you and you are your voice. Without it, you feel rather like Ariadne -- not precisely dead, but not precisely alive either. And rebuilding isn't an overnight job, either. Our voice is not just an instrument for music, it's integral to our body's survival system. When your voice is injured, your body starts doing all sorts of "helpful" things to try to preserve the voice. After all, your body reasons, if something I happens, I need to be able to scream, to communicate! I must help! Only, the problem is that what your body does to help simply makes it worse.
There are some in the opera community who treasure being blasé and make comments along the lines of "Too bad! Next!" But even if it were solely his fault (and it rarely is -- there's a whole money making machine behind a singer, deaf to anything that might take a little money from them), I submit to you that this is a tragedy for him, not just as an artist, but as a human being. If an olympic athlete were completely crippled in an accident, we'd mourn his or her lose, no? This is no less than that, and I should know...I've been there.