Well the Amiga never had the "best" CPU, the 68000 was already 6 years old when the Amiga 1000 was released in 1985. So forget a new Amiga with the latest Intel chip, I don't want any such dirty architecture. I would actually prefer to go for an Arm chip, they may not match an i7 for raw power but they are so much neater in terms of design, and if desktops are really dying then x86 is likely dying too, where as Arm is on the ascendant.
I personally don't think desktops are going to disappear, there are still plenty of places for them just maybe not all the same places. For one thing, in some applications a full-size screen and keyboard is a must. I couldn't imagine doing my job on a tablet, or even a laptop to be honest. But I do use a PC that is fairly low-powered.