This seems like a false problem. The state you are describing is not stable, as validators have an incentive
1) to validate, instead of just sitting doing nothing
2) to choose the chain with the most likely chance of being the next main, otherwise they will be slashed
As soon as even the slightiest imbalance appears between the two forks, it will bias validators to choose one against the other and thus exponentially make it the preferred fork.
> and that external incentives don't outweigh enclosed ones.
I think this is actually the most commonly overlooked assumption. The protocol seems very robust, *assuming* perfect information (aka all incentives are known to the system).
I encountered this problem a few years back when trying to design a protocol for a decentralized prediction market. It's very hard to account for hedges or huge bets on other markets.
1) to validate, instead of just sitting doing nothing
2) to choose the chain with the most likely chance of being the next main, otherwise they will be slashed
As soon as even the slightiest imbalance appears between the two forks, it will bias validators to choose one against the other and thus exponentially make it the preferred fork.