That point is actually already here for a small % of people around the world. It will eventually expand to more tech savvy users and to normal people. However, you’ll be either carrying extra accessories (keyboard, mouse, gamepad, hdmi cable, hdmi converters, etc) with you or having each set of them at your work or play station place. As smartphone will continue to evolved to the point that it just become a hub that you carry around with you. When you go home, you would still need to connect it to accessories to make it well… more accessible in a comfortable way. Same situation once you’re at work, etc.
If you don’t want to type on a tiny phone screen, you can use wireless keyboard and mouse to connected to it.
If you don’t want to look at a tiny phone screen, you can hardwire or wirelessly screen share to a bigger display.
If you want to play more graphically intensive games ment on a PC, then personal cloud gaming (build your own PC and stream it to your device) or subscribe to services with it such as Nvidia’s Geforce Now or Google Stadia (in the near future) to get your premium gaming on. You can combine this to #2 and enjoy it on a bigger display.
If you don’t want to game on an uncomfortable on-screen touch controls, then get a wired or wireless controller for it and game more comfortably and naturally like you’re on PC/Console. Though, on PC games, you’d be using keyboard/mouse setup depending on the game, such as MOBA/RTS genres.
Need a Powerful PC to do intensive computation work, such as rendering or video encoding? Do so with Cloud Computing, renting a very powerful virtual PC over the internet, remote controlling the workstation from your phone as if the phone is the PC itself. Do any task on the phone like you would normally do on your own PC. On the go or at a station connected to a bigger display.
The possibility is already all here.
All in all, while “you” can technically not need a laptop, pc, game console, etc. You would still need those type of “services” to enable you to do those things on your phone that it lacks.