I feel that Oda waited to long showing what Dragon is capable of, the only way to make him relevant now is to make him the final villian.
The same aplies to Shanks.
Both will job in a shitty way or live long enough to become the villian.
Well, I'm hoping for Shanks to be anti villain at least, let's say Luffy meets him as final obstacle before Laugh Tale after beating BB, goes to greet him but uses FS and sees Shanks would cut his arm off.
As for Dragon, I simply don't care anymore, lost any interest during Reverie arc when his commanders invaded Mariejois while he sipped tea with trannies.
Dragon will act like a big savior of the world after Luffy destroys WG and he will come in to act like a good lord.