This is pretty much the future of computing. The Nintendo Switch does it, and this phone now does it. In fact, I would be very interested to see a new phone-with-dock, that, like the Switch, has extra processing 'oomph' in the dock, so when you have your phone and dock connected, you get a powerful desktop PC, capable of running all the apps you already do on your <chosen OS here> computer.
In fact, I would go as far to say that, with the current trend from Microsoft to, well, be completely , that this might just be a opening for mobile software and hardware developers, to seize the moment. Assuming they can drop some of thedata slurping, and start advertising these things as private, safe, secure and all the rest of the things serious users would like to actually hear, I forsee a future without desktop machines.
Let's face it, desktop GPU's and CPU's are great, but expensive. They cannot fit into a phone - it just can't happen. But stick them in a dock, and suddenly you have a platform of update-ability, where the dock could be upgraded separately from the phone itself. So you still get upgrades, and it'll still work with the dock of choice. The Switch proves this does actually work.
I like this idea. I like desktop machines too, but I wonder how long it'll be before mobile phones have the same processing power than your desktop does. I'd wager it isn't all that far away.