I have a desktop PC, Macbook Pro, and an Ipad.
I highly doubt i’ll ever upgrade the desktop, and it will eventually become a file server of some description. The Macbook Pro will eventually get replaced by something like a Macbook Air, as i want the full blown OS experience whilst on the Road. My MBP is a pain to carry around everywhere.
I could potentially imagine a scenario where i would only carry around a tablet, a foldable keyboard, and something to connect the tablet to a screen, and all my development would be done via remote desktop or something.