What does one do if existing hardwood flooring is no longer made?

If you are putting the house up for resale, carpet the rooms next to the existing wood flooring. Let the buyer's decide to do what they want. What you want is to sell the house and CLEAN is the way to go.

Are you going to live in the house? Or doing this strictly for resale? If only for resale purpose, chat with several local Realtors and see what they suggest. Every market is different. If for resale, just put down the cheapest flooring that coordinates with existing flooring. If the new owners want to update the flooring, it is up to them. If you are going to live in the house, choose what best suits your taste. Great curb appeal, a tidy yard and a spotless house will sell.

I would not stress over something so minor. Focus on the important issues. What does your agent say

I would go with the closest match or carpeting.

I love the real oak flooring that I have lived with for a long time, and if I were the buyer I would be hoping for the same quality. So many houses near me have been through intense remodeling ( after being sold) it seems a waste to invest in anything unless YOU like it and will enjoy it while you are there. What product would still look good when you are really ready to sell?

Start from scratch. Have it all done with new different wood, otherwise you'll never be happy.

contrast every time. as a close match will never look right ever .......