That sounds pretty doomed to me. They're saying that mass destruction is inevitable, and the best path forward is to protect habitat that's got the best chance of future regrowth. Of course, "best chance" is according to imperfect modeling and optimism that people will actually get their shit together on the Paris treaty in the next 30 years.
And if 70-90% loss doesn't sound like "doom" to you, may I have 80% of your assets?