"Facebook Messenger is unlikely to embrace cryptocurrency payments anytime soon according to David Marcus, Facebook's vice president of messaging."
If it's a trend, why Facebook is unlikely to use crypto payments?
The answer is simply : It is not their own technology. They want full control over the technology that they want to implement.
I seriously think that Facebook would be announcing soon that they would be launching their own Blockchain based technology
for Facebook. These guys will only do something, if they can profit from it.
{Expect this technology to be stripped off all
anonymity, because they report to the US government.}