The only viable answer is to replace both airports with an airport that has DSA's aviation characteristics and yet is much closer and more accessible to the thriving Leeds City region as well as all other parts of Yorkshire.
You can't "replace" Yeadon and Finningley, the owners probably would not agree. So Yorkshire airport #3 would be competing with them.
Not going to happen. It's as futile an argument as the Boris Island nonsense.
Yes I agree but as you've more chance of hell freezing over than convincing out anti aviation politicians to build another airport, DSA is the next best alternative!
Politicians don't build/extend airports, they just put obstacles in front of those who want to.