Apple seems to be playing both sides of the argument, encouraging people to use the iPad as a laptop replacement, while expressing concerns about the ergonomics of doing so, as an argument against touchscreen laptops.
“We really feel that the ergonomics of using a Mac are that your hands are rested on a surface, and that lifting your arm up to poke a screen is a pretty fatiguing thing to do,” Craig Federighi, Apple senior vice president of software engineering, said in an interview with Wired.
Some people who use laptops for specific tasks could use an iPad as replacement. Can’t see how I could use an iPad as a developer and I don’t think apple has any illusions about that. Also, he is right. Laptops have a different form factor so it is very difficult to place a screen in an ergonomic position for touch input so the keyboard would not get in your way.
One could think about a convertible, but they are bulky, not really portable and would still require a separate ui in the « tablet » mode.
It all depends on what you do. I am mostly in MS Office, a web browser and email, all day every day. Also using the great writing tools like Ulysses, MindNode etc. I could easily go iPad only, if not for corporate policy.
Touchscreen on the Mac would be a challenge due to the small UI targets that are fine for a mouse / trackpad, but less precise with your finger.