If they successfully implement it, I think it's time to say goodbye to social media project startup who do an ICO last year. I still remember one of them, at this moment they have serious difficulties in product development. Luckily I don't spend my money on those low-quality project.
ICOs usually suck,but don't be so sure that Facebook will implement blockchain technology soon.
Such implementations would require billions USD to be invested and years of programming and development.
During that time,FB will continue to sell all our data to the advertisers.