Here is a summary of the on chain futures contract:

For anyone who thinks BIP 444 will activate, I will happily offer you an ability to make more bitcoin.

We each deposit 1 BTC into a taproot address with two spending conditions:

1. Time locked so that you can withdraw June 1st next year at a depth of 1 in the tap tree.

2. Time locked so I can withdraw May 1st next year at a depth of 128 in the tap tree.

If BIP444 activates, you get 2 BTC out of the address (because my spend path would be consensus invalid).

If BIP444 does not activate, I get 2BTC out of the address.

DMs are open, we can use a dedicated escrow agent as third key if necessary, would obviously provide auditable code to show there are no tricks.

We can also atomically fund the transaction using a multi input transaction into this taproot address to guarantee all parties fund the address.