I think it's a reference to Fukuyama's "end of history." It's not that history or mobile computing reached their end, but that the significant conflicts between world views and computing platforms are over. In history, the West won the Cold War. In computing, mobile won.

It's the end of growth in mobile, though he doesn't really make that explicit.

It's more clear if you put the quotes differently: the end of "mobile". Since it's mainstream, there's no reason to list it as a separate fringe category.

Yeah, it just means people are buying devices less frequently

"Mobile" (however defined) is obviously not going anywhere. I think it's just a click-bait headline