What became of Mainframes?

"Mainframes will soon be extinct", is what the "supposed to be" experts have announced regularly. Yet nobody told the mainframes, which still remain alive and well, as the backbone of world banking and other business systems.
The reliable and secure, mainframes are seldom in the limelight. But one probably approved your last ATM withdrawal or reserved your last airline ticket.

What's most impressive, though, is that NASA launched a rocket into space, guided three astronauts to the moon, landed two of them on its surface, returned them to their original craft and brought them home again with less computational power than you've got in your iPhone.