All teams, no matter what the sport and no matter what the previous success level, goes through down times. The likely end of Steve Nash's career, along with the injury to top pick Julius Randle, is a sign that it is indeed the turn of the wheel for the Lakers. One last victory lap for Kobe Bryant, and he could possibly end his career with another team while the Lakers rebuild.
The Julius Randle injury is just the latest in a series of setbacks that is not over yet, and won't be over until Kobe Bryant is gone. They have lost key players such as Dwight Howard and Pau Gasol in free agency and failed to sign a major free agent themselves because no one wants to play with Kobe. The injuries to Randle and Steve Nash could be overcome if they had quality depth, but they don't. Until Kobe, his ego and his massive salary are history , the Lakers woes will continue.
No, Julius Randle's injury is not an omen of things to come for the Lakers. When you play professional sports, there are bound to be injuries. Players get injured every day, and the next person on the bench needs to step up. There is no "guiding force" behind this, it is just the nature of the business.
It might be an omen for him personally, but as a team they should be able to pull together and figure out a good game plan that excludes him. If they can't do that, then they were not a good team to begin with anyway. A good team can pull it off.