THIS is firmly Luka Doncic’s team now after LeBron James left behind the Lakers — and his oldest son — to chase another ring in Philadelphia, and the reigning NBA scoring champion seems determined to demonstrate his ability to carry a team deep into the playoffs.  Doncic spent the offseason getting into top shape after mis-sing last spring’s playoffs with a hamstring injury, and he invited the entire roster on a bonding trip to his native Slovenia.  The Lakers will miss James’ playmaking and reliability when healthy, but Doncic and high-scoring Austin Reaves lead a roster that is deeper than last season, according to Redick.  It’s definitely younger, and it should be better defensively. The Lakers brought in nine new players in the latest summer of total roster upheaval, but they believe this group will stay together long enough to turn into a true title contender.  That’s largely up to the brilliance of the 27-year-old Doncic, who is squarely in his prime years as he chases his first NBA championship. The good: Doncic remains one of the NBA’s most brilliant offensive players, and the undrafted Reaves has grown into a dependable counterpoint who deserved his $185 million extension.  The biggest addition is center Kessler, who fills Doncic’s desire for a rim protector and lob finisher. Kessler has been dominant at times when healthy in his brief NBA career, and he appears to embrace the challenge of playing under Holly-wood’s bright lights.  The Lakers are indeed deeper, with guards Sexton and Grimes leading a new supporting cast. The not-so-good: It’s hard to imagine the Lakers being more than mediocre without Doncic, whose health will be paramount.  He hasn’t played in more than 70 games since he was a rookie, and he managed only 64 last season.  Reaves has carried the Lakers for short stretches without Doncic and James, but he was limited to 51 games last season. Kessler played only five games for Utah last year before starting the preseason deliberately, but he expects to be at full health.  The Lakers also need somebody to step up as a 3-and-D contributor on the perimeter, but they have several good candidates.