Courtesy of GucciWhen you already have a holy grail fashion piece, what comes next? Wearing a revamped version, of course. That’s what Kim Kardashian did this weekend with one of fashion’s most viral and risqué designs: the Gucci thong.On Sunday night, Kardashian left Monaco by boat after supporting boyfriend Lewis Hamilton at the Formula One Grand Prix. Her seafaring attire? A long-sleeved, sparkling black Gucci gown with a plunging open back a…