I'm not sure about Doctorow's conclusion that enshittified services die. They will go worse but then rise to the minimum level of shit people can stomach and also use all their capital and influence and power to maintain their position. Including things like lobbying for more regulations that they can afford but newcomers can't.
The obvious answer is the fediverse where accounts are not owned by one service. But it still has a long way to go and could fail, could be sabotaged, could splinter, could be regulated into oblivion, or could just fail to get enough people on board.