In a half-bitcoinized world, I don't see many incentives to destroy Bitcoin, because people don't want to lose their money.
ok, but here is my answer to consider too, an slightly modified version of Prisoner's Dilemma short description:
"The Prisoner's Dilemma is a standard example of a game analyzed in game theory that shows why completely rational _ large Bitcoin holders _ might not cooperate, even if it appears that it is in their best interests to do so."
in other words: "It's not a problem I'm switching-off my Antminers "for a while", because other holders will surely keep it running at loss... because they don't want to lose their money, ha"