Beyond the human tragedy of a talented life cut short, Scott's death also halted a group on a seemly unstoppable roll. After a steady seven-year climb from the Australian club circuit to the verge of worldwide megastardom, AC/DC suddenly faced serious doubts about whether they had any future at all. They even considered folding up shop and quitting altogether. After much deliberation, though, the remaining members of AC/DC decided to soldier on, believing it's what Scott would have wanted. A number of replacement singers were considered, including ex-Moxy member Buzz Shearman, Terry Slesser of Back Street Crawler and Slade's Noddy Holder. Then there was a bloke named Brian Johnson, who fronted the band Geordie…