Note that with the iPad, Apple is doing everything they can to hamstring the ability to code or replace the Mac.
Now expand your field of vision to Surface and Pixel Slate, and now you have two fully featured computing devices that act like a tablet, but readily convert to full on productivity machines complete with nice keyboards and pointing devices. Both support external monitors (why on earth can I not use airplay like this?!).
This hasn’t caught on yet, but for the average office user, and event many developers, these tablets with external keyboards provide more than enough computing power to get all of their work done.
For now I’m staying with my iPad, but Google has really made that choice a lot more difficult with the Pixel Slate. Had I been less bought into the Apple ecosystem, I’d be ordering it immediately.
EDIT: Forgot to mention eGPUs - if I could run a Thunderbolt3 eGPU on either Surface or Pixel Slate, probably would have switched by now.