Perhaps that’s not the right dream. It gives undue weight to your contribution to a future that might not need it, nor want it. A current impact that improves things is definitely a delight.
If you stop an asteroid from destroying the world then obviously you are improving the future and the present and those are the only types of lasting impacts we need.
The only thing improvable is the present because the future isn’t here yet. People in the future will likely know more about their problems than you guessing about them from today. Let them make their impact in their present and you make yours today. Forget about that lasting impact, you’re not smarter than the smart people from the future, and they know more about their realities than you do.