Ask HN: Holding crypto currency in custody in the case of a fork?

Currently it looks like Ethereum will experience a forking attempt by miners who are not happy with the EIP-1559 proposal which would reduce their revenue.

Vitalik and Co are reacting by speeding up the planned fork to proof of stake which will cut out POW miners altogether.

If you are holding Ethereum on an exchange like Coinbase or some trust like Greyscale or 21shares, I wonder what happens in the case that it forks into multiple chains with significant market value.

Ethereum forked once already and the smaller chain (ETC) still holds about 0.5% of the value. In future forks it might be less unbalanced.

This applies to Bitcoin and all crypto currency in custody of course. It is just more imminent for Ethereum.