[beaugunderson]

> Yet this can't happen.

You don't even need to perfectly predict the next state to make risk-free attempts; you merely need to submit your transactions using flashbots (which operates a gateway directly to the miners). You pay a portion of your profit to the miners as an incentive to include your transaction, and if your transaction fails for any reason it fails atomically and is not included in the block, meaning you have paid no gas and your attempt is thus risk-free. One caveat is that this only works if the transactions can be assembled into a bundle within the same block.