What I suspect will happen is that we'll eventually get a block larger than 1 MB in the blockchain and Core will adapt their codebase to permit its users track the most-work chain. In other words, there will likely be no split--just an anticlimactic network upgrade to larger blocks. In such a case, who wins the bet? Or is the bet only valid in the case where there is a persistent split?
It's absurd to think that there is not a
single miner who will continue operating under the old network rules -- and that's all that it takes to create a persistent split.
It's seemingly this very lack of critical thought that leads to BU not being able to make even minor changes to the client without introducing bugs and vulnerabilities.