So if Matthews plays a full season next year and scores lets say 80 points will this debate be over for a while? Imo Matthews doesn't have the playmaking ability to match McD in points, but he will probably always be the better goal scorer. The speed at which McDavid can handle the puck is generational. McDavid had both more assists and more EV points than Matthews had total points this season.
Matthews has a suite of elite skills (and no weaknesses) that make him an elite player, but he has no individual skill that someone else in the league can't do as good or better.
McDavid has a suite of elite skills and a generational skill (skating/puck handling combo). No one else in the NHL can handle the puck at the speed with which McDavid can handle the puck, and that's what makes him "generational."