The game-theory problems of PQ sunsetting modes

The email presents a detailed analysis of the challenges and implications associated with executing a chain rollback in blockchain environments, specifically referring to a scenario where miners might opt to mine an older block chain rather than continuing with the more established one. This process involves significant strategic shifts and risks, particularly when considering the incentives and potential outcomes for those involved.

In this analysis, it's noted that for miners to initiate such a rollback by mining what is termed the "revisionist" chain, they would be required to abandon the currently accepted ("authentic") chain. The authentic chain is where most users have already migrated or forked to. The feasibility of this action hinges on the collective decision of the miners to forego immediate rewards from the authentic chain, as any effort put into mining the revisionist chain would not yield returns unless its cumulative proof-of-work surpasses that of the authentic chain. During this period, honest validator nodes would not be active, essentially waiting out the outcome.

Furthermore, the success of mining the revisionist chain would also involve a sort of betrayal to the system's integrity, resembling a massive double-spend attack. This would lead miners to negate their own previously mined and possibly sold earnings on the authentic chain, an action that could upset exchanges and invalidate previous financial transactions made with the mined coins. The consequences extend to potentially being ostracized by these exchanges and dealing with the depreciation of the value of the bribes (in coin form) received to undertake such mining activities.

Lastly, the discussion raises concerns regarding the viability of shallow reorganizations of the chain (reorgs), involving only a few blocks, which still pose significant threats to the network's stability. These concerns suggest that preemptive measures, such as deploying an EC disabling fork, could prevent the introduction of such high-stake incentives, thereby protecting the network before these risks materialize.