I think it's inevitable, but I don't think Facebook will be first to get it. It would be cool if gab.com integrates it, then I might actually use the site more.

Twitter seemed close to getting it with Jack Dorsey being such an advocate, but I'm not sure if he has enough sway.

It's hard to start a new social media site from scratch because the other sites have benefitted so much from years of network effects.

I think it would definitely be worth developing and stacker.news and fountain have proved its efficacy. Even just the use case to root it spammers is a game changer for sites like twitter. LN might need more liquidity than 4K bitcoin if a huge site like Twitter were to implement.