Certainly there would be an upgrade cycle, but it would be the cycle of the desktop rather than the laptop. Laptop upgrades typically require whole machines. You can do a little bit with PCMCIA cards, but its nothing compared to the piece-meal upgrading you can do with desktops.
You would do mouse and keyboard with a mouse and keyboard. They would either be wired to the screen, or wireless in their own rights. TFT on-screen keyboards are terrible, terrible input devices that shouldn't be considered.
You could make the screen have a PCMCIA card slot for the wireless adapter, making it updatable too. 0 need to stick with obsolete wireless tech in that case. Monitors can last a long, long time.