I'm not sure if this is what you're asking, but I can confirm the buttons are still there for me using Win 7 + Firefox. So they haven't disappeared globally but I can't say whether it's an iOS 10 related issue.
Ok thanks for confirming this. I still see them on my computer with Safari as well.
So might be an iOS issue or a HTML/CSS check that is hardwired to decide dynamically whether or not to display the buttons based on browser version and suspected capability