It is a great post, and I am optimistic about the future of Steem and Steemit, but I think you're underestimating Facebook. Facebook is not Mark Zuckerberg - there are a lot of talented people there, who've built a juggernaught - and one which won't be de-railed easily.

Yes, they'll have to adapt to the challenge of blockchains, decentralisation and tokens, but they don't have to do it the same way to compete, or stay ahead.

Even if they didn't do anything blockchain-related, they could introduce a totally centralised Facebook token to reward their audience in some way - and they'd happily lap it up and be delighted to get anything.