How about this, good faith way Facebook will still destroy everything

Facebook does one way, minimal federation. Facebook trash content makes its way around the fediverse, but things are mostly the same. Vigilance goes down

Facebook does complete federation, but at the same minimal level. Threads users now get to vote and comment on some fediverse content. This is the peak benefit to the fediverse

Facebook slowly ramps up data flow in both directions. The fediverse has smaller numbers and minimal tools to manage federation.

Facebook has an algorithm, a complex system to manage content to maximize for time/interaction/tolerance to ads.

Threads content will have far higher metrics that will impact our basic sorts, because the algorithm picks winners and losers. Fediverse content shown on threads and chosen by the algorithm also blows up

The various fediverse projects scramble for solutions. They might change up the sorting algorithms to adjust, some try to manage federation granularly (such as not counting threads votes, or treating their content differently). But they need tools that handle granular federation across the board, and they need it without breaking compatibility with activity pub... Every change will roll out slowly, and it's a very complicated problem.

Threads can update whenever they want, and can change how they federate far faster and more easily, because they're a centralized platform just deciding how they want to push and pull from external sources.

Some might cut off federation at this point, and users are pissed off they kept being shown the same content, and now are getting even less content.

Others are pissed that their feeds feel like Facebook.

This is the best case scenario... Just like Bitcoin or Tor, a decentralized network can be manipulated by any party who owns over a certain percentage of the network. They'll be able to control which content we see on the fediverse, because their numbers and algorithm will overwhelm our own.

They could also attack the standard and use standard EEE practices, but even if they don't, they'll enshittify the fediverse just by nature of the connection