Dethroning Silva: Could one of these five fighters have what it takes

Anderson Silva (32-4) is the reigning UFC Middleweight Champion. He has been called “a mutant”, a “freak of nature” and “the greatest martial artist of all time”. With 15 straight wins in the UFC spanning over 6 years, the question I am most often asked by fans, fighters and fellow scribes is “What is it going to take for someone to defeat Anderson Silva?”
There is no quick or easy answer. A shift up and down to the wrong weight class could be his undoing, likewise age could start to catch up with him, but