These struggles are not new - remember the 9 boxes diversification strategy from Buzzfeed last December. For some publishers, the past months may have offered enough room for maneuver to pivot in business models or at least diversify to a number of distribution channels (and monetizaton models along with them), but the bigger the operation, the harder it is to achieve (for example Little Things had to shut down, Slate, Mashable, Vice lost over 60% of traffic referrals from FB).
Facebook's biggest video publisher in recent years, Unilad, now seems to face really serious problems, maybe even insolvency. Hard to imagine we won't have a similar discussion in a few years with Instagram- or Whatever-platform-dependent publishers. I'd still recommend to milk the cow, but grow a few others besides the big fat one in case it runs dry.
Digiday says that for Unilad, "the writing is on the wall":