What would Aragorn have done in the Hobbit movies?

Viggo Mortensen, the actor for Aragorn, was offered to be Aragorn in the hobbit movies, but refused the role because the character Aragorn wasn't in the hobbit.

Did they even have a plan for the character by the time Viggo declined the role?

If he had accepted, how would this have changed the story?

I would like to point out that this is not a duplicate of Could Aragorn have been featured in The Hobbit: An Unexpected Journey? The answers to that question are concerned with the possibility of a young Aragorn/Estel in Rivendell, and I find it rather unlikely Viggo would have played a 12 year old ;-)