Suppose I thought the current housing market was inflated, and I expected prices to go down in the future. However, I still want to buy a house. So I'm thinking, does there exist a contract where
The buyer agrees to pay 10% of the market value of the house on each Jan 1 of the next 10 years in exchange for the house?
Of course the seller needs some money up-front, so I can see this packaged as an up-front purchase for the current going rate, plus the sale of a swap. In the swap, the home-seller pays the home-buyer some amount for the right to receive from the buyer the market value difference of the house (or vice versa). Of course then there are complications like, what if the buyer intentionally trashes the house, etc., but those don't seem like fundamental obstacles.
My question is: Do schemes like this exist? If not, would it be hard to set one up when buying a house? Are there any legal impediments?