I think the chance is proportional to how much ETH insiders have staked. As this depression deepens, unempoyment will start rising (especially after New Years) and consumers will start dumping cryptocurrencies. ETH will fall in price and ETH insiders (e.g. Joe Lubin) will demand that Vitalik enable unstaking so they can sell too.

Once unstaking is enabled, it will be a race to sell first. But those who have not staked their ETH will have a chance to dump first. In other words, Vitalik would enable staking in reaction to the dumping of unstaked ETH.