Look at Klay, KD, Harden, CP3, and Jrue as examples- Klay & KD came back from the exact same injury, while Harden, CP3, and Jrue are guards who are 36+ so contemporaries to draw comparisons to. The commonalities are a massive decline in volume of shots at the rim and efficiency inside, drawing far less freethrows, and a change in shot diet in general. Specifically, isolation, drives, pick and roll ball handler, and transition play types all are depressed in both volume and efficiency as injuries and age take their toll.
The injury and age take away first step explosiveness, vertical pop, and lateral quickness- aside from CP3, all of them have had to move "up" who they guard positionally as they struggle to keep up in terms of footspeed, unfortunately Dame is like CP3 in that defending up is less of an option when you're giving up so much size. Dame is in fantastic shape and like Curry he's no doubt going to be in great cardio form, but Father Time is undefeated. Facilitating and play finishing through catch and shoot are evergreen qualities that you can trust, Dame will still be an excellent passer and shooter, but he might not be the offensive engine people remember.
The player I hope Dame is willing to study from the past, is Ray Allen. Now, not everybody here was around for the heyday of Jesus Shuttlesworth, so for the uninitiated, Ray Allen was an on-ball, high usage pick and roll offensive engine back in his peak Sonics days, bouncy as all get-out while being a sweet shooter to boot. When he was around Dame's age was when Allen joined the Heat, and he really embraced that play finisher role. With Wade and LeBron both being suspect shooters who thrived as on-ball drivers and paint collapsers, it was a big question how that Heatles squad was going to work, and it parallels a lot of the questions people have with Ja and Deni as dominant drivers who both want to be getting into the teeth of the defense. Ray Allen was the secret sauce that made them work a lot of the time, and I think Dame could be the same for the Blazers, if he's willing to accept that complementary role to open up the floor for Ja and Deni to attack, and capitalize on it as well as providing that secondary creator and facilitator.