I sympathize with your point of view. On the other hand, it seems like you could take your comment, replace "PC" with "mainframe" and "mobile" with "PC" and it would be right at home in 1975 or so.
It's interesting because the 1975 version of the comment would be absolutely right. The PC did herald the end of the mainframe as we knew it. Sure, they're still alive, sort of, but it's not like it once was. And yet, the transition ultimately ended up being wonderful. Maybe this new transition will be great as well. Let's hope so.
The difference is the backwards shift in the user interface this time around. The touch paradigm is fundamentally less powerful and efficient than KB+mouse. Conversely, a PC can do anything a mainframe can do, from a UI standpoint. The true supplanter of the PC must have parity in this regard.
It's interesting because the 1975 version of the comment would be absolutely right. The PC did herald the end of the mainframe as we knew it. Sure, they're still alive, sort of, but it's not like it once was. And yet, the transition ultimately ended up being wonderful. Maybe this new transition will be great as well. Let's hope so.