I Predict Failure...

Okay, so the main reason that NBC's Americanized version of the British sitcom Coupling fell on its face was that, from all accounts, it stank. I say "from all accounts" because after watching two or three episodes of the lame original, I never even bothered to check out the American remake. However, there may be another reason for Coupling's failure which may also doom NBC's newest Brit-com remake, The Office: it's redundant.
Now, there is, of course, a long tradition in American TV of adapting British sitcoms for consumption acrross the pond. All In The Family, Sanford and Son, and Three's Company are all taken from British hits. However, I believe that era has come to an end thanks to BBC America. Back in the "Golden Age" of Brit-com remakes, the 1970s, few, if any, Americans had seen Til Death Do Us Part (All In The Family), Steptoe and Son (Sanford and Son), or Man About The House (Three's Company). These days, however, thanks to cable channel BBC America, not to mention PBS and DVD sets, quite a few Americans have gotten to see Coupling and The Office, so we don't really need a remake.
By the way, a recent Columbus Dispatch feature on Brit-com adaptations omitted Too Close For Comfort, adapted from Keep It In The Family, which was a mild success, lasting three years, yet did mention the two failed attempts at an American version of Fawlty Towers, which, I believe, lasted less than one season between the two of them.