I haven't seen many addition to the periodic table lately
Well, except for unobtainium.
most excellent observation.
What about Adamantium and Vibranium?
I don't think this Doomsday Scenario will be the case. As Steve Jobs once said, we will always need trucks. While most people can do their daily driving in (relatively) easy to use cars or even commute by mass transit, we still need trucks to move around the big items. Music and video production, intense graphics, animation, etc. will still require more powerful (and probably different interfaced) hardware. I realize there have been points where the performance of the iOS devices are better than macOS devices, but I don't think Apple will let that go on forever. They know that they have a base of pro users in Logic Pro and Final Cut Pro. I can't foresee someone editing a real movie or audio production on an iPad, not without external monitor(s).