There are no maturity requirements to run a company.
I'm not as optimistic as you are about his predictions. Just about every company seems to use Facebook nowadays, brick-and-mortar shops have images of Facebook's Like button on their windows, and plenty of job postings include Facebook links. Smaller companies don't even have their own web pages, they just use Facebook. I also wouldn't be sure that everybody even knows Facebook's internal messaging systems and e-mail are completely different animals. Messenger and ICQ were tiny compared to Facebook today. I don't use it myself, and don't want to sign up in order to apply for a job, but I'm afraid it's not implausible.